I think it comes down to opportunity to use the 50/50, and cost of guessing wrong (for both players).
Take Cutthroat Kano- He has 50/50s, but B1 practically hits on his toes so far as range. Therefore, you're not in danger of the 50/50 unless he's able to run right up on you. That keeps the (rather amazing) tool out of play if your opponent actively works against it. The trade-off is that the 50/50 is completely safe. Sidenote- most people that like the new Charge Up buff like it for the wrong reason. The only way it adds to Kano's game is to use an advancing string to jail into allowing Kano to use Charge Up and follow up with a guaranteed 50/50 attempt. This adds range to his 50/50, but it also adds risk it doesn't have normally, because you're constantly taking damage the whole time. If they guess right, you're taking a lot of damage to no benefit.
Take Raiden (all variations)- He has 50/50s, and tons of damage off them in the corner. BUT, without the OS (or absolutely insane reaction speed), his B2 is incredibly unsafe. Whiff or Block? Full combo punish town. So, while he has 50/50s that can help him win a match, they can hurt him just as much. It's the definition of a double edged sword.
So just having 50/50s doesn't automatically move a character up a tier based on luck. It's about how the 50/50 option affects both characters. That's why I don't think Raiden is amazing even though he has great 50/50 damage. His opponent also has great 50/50 damage, because Raiden effectively 50/50s HIMSELF while he coinflips.