Outburst warning from a grumpy programmer, lol
From my experience, I tell you this wouldn't work - fans can be extremely annoying and toxic at times.
If I only add one character from a famous group, like TMNT, fans will insistently ask for the other 3 and I would have to spend 3 slots in the game just for that.
It's the same reason I didn't add the Fantastic Four to my Avengers game: if I put one character in, they'll ask for the other 3 (and then every other character they've ever been a part of). Over and over. And I don't want to spend 3 new slots with the other characters
I already experience something similar in the Power Rangers game: No matter who I show in the game, people just ask for the Green Ranger. Over and Over. Just like they keep asking for all the formations that ever existed. So much so that if it were up to me, I wouldn't even put the Green Ranger on anymore.
TL;DR
I have a philosophy as a programmer: I only add new content that brings something new to the project. So to add a new character to a game, he has to bring something different to the project.
Personally, I hate the concept of adding a new character just to have something new, while it basically functions as a skin for another character. So I prefer to add a skin/palette/custom. It's one of the reasons I didn't have She-Hulk playable in my Avengers game - she would just be another super strong character, there's nothing new she could bring to the game. The same goes for the Thing.