>>9215857We all know the reason they don't usually have such radical differences is for budgets sake, the cost piles on (more so if you want the actor to be able to see and move) if they have to make a custom neck or torsos to match the rest and I'm sure there is some r&d to consider with it as well so keeping the system simple is a cost covering measure. Comics are not restrained in the same way so they can do more with it.
As for Shredder it's not unheard of for suits to take wild changes based on outside factors such as magic and what not, and sentai have worn cloths under and over their uniforms effecting the look.