As I have said before, developers needs to make tons and tooooons of money really bad, because expensive and fancy servers for us are no free, or cheap.
So selling theonite for rellics is their main money income, so if they can´t sell the oportunity to gain a certain rare character, people will just stop buying stuff in the game.
Actually, RNG can be a little negative in your odds (Ok, a b*cth), but this is a GLOBAL game, and is made so if you are reaaaally lucky enough (And with lucky I mean PACIENTE) you will pull a really good char. Not the one you are looking for. but a good one
If you can give them the fighter, the basis of the game dies, and money income dies, and so SGM dies... so it´s not a win win situation, and therefore, I don´t think it would be considered like a even viable idea.
good daaaay!!