I should add that all of the melee-centric classes I've added have been deliberately thought out.
Fei is a footsie/offensive pressure character in a game where footsies reigns supreme. Adding him to INS Mod would make no sense because close range footsies doesn't work. There is no general blocking/blockstun, knockdown, frame advantage on hit leading to combos, or animations that freeze the opponent from being able to do anything (like ultra 2).
He has nothing that would make him stand out, and would probably get kited to death against every other class. The melee classes that are in the game have ways to avoid getting kited, with fast speed (bo jackson), dodge/movement skills (samurais, dante, kid, bo jackson, jaina, honda), stealth (chryssalid), or other options at longer ranges (jaina, dante, kid).
If you'd like to see him have a chance making the cut, you could always:
If you want to see these classes, you should get into spriting and modding yourself. That's where I started; I just wanted to make cool shit.
additional hint: people have done this before and gotten stuff in
Dusty, Killah Zillah, and Wareya have all contributed playable classes.