In all of those instances, we have no reason to believe that they were far away from full power. Being 50% is a lot different than being 80-95% for example.
Should it be big? Yeah, but not like what some have. A sample 50% = Warm up list.
SSJ G2 Vegeta: 100
Warm Up Cell: 180
SSJ G3 Trunks: 250
50% Goku: 180
100% Goku: 360
Cell @ Goku: 406
SSJ Gohan: 504
I don't really see a contradiction there... Cell is at a level where he can tank Vegeta's kick, and Trunks is still at a level where he can demolish Cell.