Why did AT show Goku and Nappa fight evenly?

[withheldforprivacy]

The feeling that fight scene was supposed to give off was that Goku
came back from his cool training stronger than ever and whipped
the floor with the minor villain that had been whipping the floor
with everyone else up to that point, before moving to the real
fight (Goku vs Main Villain). Then, why, at the end of the fight
Nappa becomes stronger with a poor explanation (Goku had ''tricked
him into a fit of rage'') and gets evenly matched with Goku? Doesn't
that kill the purpose of everything built up to that point? From a
writing point of view, it'd have been better if the part where Vegeta
tells Nappa to calm down and magically transforms him into a worthy
opponent was omitted. It'd be more correct if, after getting ragdolled,
Nappa used his mouth blast right away, Goku deflected it and Vegeta
called off the fight.

 

[Let's Go Fearless!]

They weren't that evenly since Nappa can't even hurt Goku. But still Nappa is worth of trouble for Goku though.

 

[freezamite]

The feeling that fight scene was supposed to give off was that Goku
came back from his cool training stronger than ever and whipped
the floor with the minor villain that had been whipping the floor
with everyone else up to that point, before moving to the real
fight (Goku vs Main Villain). Then, why, at the end of the fight
Nappa becomes stronger with a poor explanation (Goku had ''tricked
him into a fit of rage'') and gets evenly matched with Goku? Doesn't
that kill the purpose of everything built up to that point? From a
writing point of view, it'd have been better if the part where Vegeta
tells Nappa to calm down and magically transforms him into a worthy
opponent was omitted. It'd be more correct if, after getting ragdolled,
Nappa used his mouth blast right away, Goku deflected it and Vegeta
called off the fight.

Because this isn't your average manga where A > B and they call it a day. By doing this Toriyama already put Goku below Vegeta, introduced the KK, used it as an example of why Goku's superior training actually matters, and gives the series much more depth, all while still accomplishing its goal of presenting the new Goku to the audience and hyping it.
What you propose would make DB a much worse series, a bad fanfiction like DB Multiverse instead of the original one.

 

[Captain Cadaver]

Toriyama had already had Goku stomp the secondary villain with Drum and would do so later with Reacoom, so having Nappa be the same would prove to be boring. Having Nappa put up some level of a fight also helped hype up Vegeta, since we were already aware that Vegeta was far superior to him.

As for Nappa's change in performance, it can be chalked up to an inbalance in his Genki, Shouki and Yuuki due to being blinded by rage.

 

[The_Authority]

Goku was obviously toying with Nappa. The only parts where he wasn't was the Kamehameha he did when Nappa got in his face and was about to blast him and then when he had to use Kaio-ken to save Gohan and Kuririn.

 

[Captain Cadaver]

Goku was obviously toying with Nappa. The only parts where he wasn't was the Kamehameha he did when Nappa got in his face and was about to blast him and then when he had to use Kaio-ken to save Gohan and Kuririn.

Goku wouldn't have stated that "this could take forever" had he been far stronger than Nappa without Kaioken.

 

[withheldforprivacy]

Well, the first time i watched this fight, that was the feeling i got. I didn't even pay attention
to the small part they were even; it was only when i got Internet access and read PL lists when
i realized Nappa was close to Goku.

 

[Evil Vegeta]

Nappa was pretty much depicted as an idiot the entire time. After getting embarrassed by Goku, he needed a wake up call unless he wanted to continue getting stomped. We got to finally see how strong Nappa was when he wasn't being a buffoon. I would've liked to have seen the fight without it being interrupted.

 

[theallpowerfulpuipui]

The feeling that fight scene was supposed to give off was that Goku
came back from his cool training stronger than ever and whipped
the floor with the minor villain that had been whipping the floor
with everyone else up to that point, before moving to the real
fight (Goku vs Main Villain). Then, why, at the end of the fight
Nappa becomes stronger with a poor explanation (Goku had ''tricked
him into a fit of rage'') and gets evenly matched with Goku? Doesn't
that kill the purpose of everything built up to that point? From a
writing point of view, it'd have been better if the part where Vegeta
tells Nappa to calm down and magically transforms him into a worthy
opponent was omitted. It'd be more correct if, after getting ragdolled,
Nappa used his mouth blast right away, Goku deflected it and Vegeta
called off the fight.

This is your brain on drugs.

 

[withheldforprivacy]

The feeling that fight scene was supposed to give off was that Goku
came back from his cool training stronger than ever and whipped
the floor with the minor villain that had been whipping the floor
with everyone else up to that point, before moving to the real
fight (Goku vs Main Villain). Then, why, at the end of the fight
Nappa becomes stronger with a poor explanation (Goku had ''tricked
him into a fit of rage'') and gets evenly matched with Goku? Doesn't
that kill the purpose of everything built up to that point? From a
writing point of view, it'd have been better if the part where Vegeta
tells Nappa to calm down and magically transforms him into a worthy
opponent was omitted. It'd be more correct if, after getting ragdolled,
Nappa used his mouth blast right away, Goku deflected it and Vegeta
called off the fight.

This is your brain on drugs.

I consume a lot of sugar. Sugar is addictive. Maybe it counts as a drug.

 

[The_Authority]

Goku wasn't even on the attack. How can anyone think that Goku was fighting evenly with Nappa when he only landed a few punches dedicated to his friends and did things to embarrass Nappa, such as hop on his head? Goku was not attacking in the fight.

 

[Evil Vegeta]

In the back and forth? Yes, Goku was attacking. Neither landed a hit on each other once Nappa calmed down.

It also wouldn't make much sense for Goku to think fighting Nappa would "take forever" if he really outclassed him. Goku didn't really look forward to continuing that fight.

 

[Diamond Ryan]

Spoiler

This is the panel that Evil Vegeta was referring to.

 

[theallpowerfulpuipui]

The feeling that fight scene was supposed to give off was that Goku
came back from his cool training stronger than ever and whipped
the floor with the minor villain that had been whipping the floor
with everyone else up to that point, before moving to the real
fight (Goku vs Main Villain). Then, why, at the end of the fight
Nappa becomes stronger with a poor explanation (Goku had ''tricked
him into a fit of rage'') and gets evenly matched with Goku? Doesn't
that kill the purpose of everything built up to that point? From a
writing point of view, it'd have been better if the part where Vegeta
tells Nappa to calm down and magically transforms him into a worthy
opponent was omitted. It'd be more correct if, after getting ragdolled,
Nappa used his mouth blast right away, Goku deflected it and Vegeta
called off the fight.

This is your brain on drugs.

I consume a lot of sugar. Sugar is addictive. Maybe it counts as a drug.

 

[Fantastische Hure]

To show:

A. Nappa already is on-par with Goku. How can Goku deal with the even higher Vegeta, if he has so much trouble with even Nappa.

B. To hype-up the Kaio-Ken. Kaio-Ken instantly defeated Nappa like nothing. And that was just a regular Kaio-Ken (Fans obviously didn't know that yet.). This seemingly in fan's thoughts might have given Goku a fighting chance against Vegeta now. But even the Kaio-Ken isn't high enough for Vegeta.

 

[ChulpaBatman]

Nappa can take a beating which is clear also. Nappa isnt super close to Goku but is enough to challenge him. Vegeta wouldnt be saying Nappa could still potentially win if Nappa was 2x weaker than Goku.