Evil Vegeta said:
Maybe I'm just overthinking it.
Nice robotic guy getting stomped on is probably all that mattered there.
Like others have pointed out, I don't think it was simply #16. The most important thing was the robot's speech, who seemed to understand why Gohan couldn't cut loose -- the reason being a mental barrier (which was presented in the final KMHMH), -- and #16's speech just helped Gohan to realize he might just set his emotions free, since there're enemies that can't be convinced through words:
Even Cell understands that as a good advice, but don't think his advice would contribute to Gohan's passions setting free.
Even #16 wants to be taken to Gohan, not because he knows Gohan would be snapped into a frenzy if he gets killed, but because he has an advice to make -- and
that is the main thing, although #16's death might also have a factor considering Gohan's face after him being crushed, followed by him cutting loose. But that
does not make it thr sole or even the main reason, the main thing there was #16 understanding what Gohan feels -- probably because he is a pacifist as well and don't enjoy fighting -- and trying to pull the anger from Gohan.
Saying #16 was the sole reason for Gohan's anger is just ludicrious to me when I just read the scene, as ludicrious as saying Goku didn't know he could have defeated fat Boo until the end or saying the Potara is the main reason for Vegetto's strength.
Like I said, it might be both -- but with #16's advise having the higher role in it.