If there is anything that MMORPGs and now online virtual tabletop gaming has revealed it is this: most players just make Expies of their favorite characters, and they favor RPGs (regardless of the medium) that facilitate the fulfillment of their Fountain of Expies fantasies.
As the above links show, people clone favorites for the explicit purpose of enjoying them as they desire when the original creator cannot or will not satisfy that urge. RPGs are very good at doing just that, so many do so. (To the point that "Drizzt Clone" is a thing, for an example specific to D&D.)
It's not Mech-Piloting, but it tends to go along with it. The player wants to play his favorite character, so he rolls a clone. This character is an Iconic Hero, and resents all pushes to change the character away from the icon as that negates his reason for playing the character and thus the game. It is this iconic quality that makes it friendly to Mech-Piloting.
While professionals clone for reasons other than satisfying personal desires (sometimes), for gaming this revealed preference shows another truth about the medium: it's about taking a man you dig and seeing if you can do that man better than the creator did. It's why the scenario doesn't matter that much--hence why Muh Storygaming falls flat--because the player desires to prove that he's a better icon than the icon's creator and that requires thinking entirely in terms of competitive gameplay and not Writing Room bullshit.
I can't say that this is bad as such. Folks clone because it's fun to play your favorite characters. The issue is when you go Full Retard about it; you're all there to have fun, so don't harsh on the others' fun by being a dick about it. It's a long-standing revealed preference, so work with it.