Alright, I'm going to say this once, and I want you to really listen. Execution requirements are not in any way, shape or form, relevant to the ability of a character unless the execution is so extreme, no human could perform it consistently. As of now, there's only one character I know of that fits that bill, and that's MvC2 Dhalsim.
Not having big damage is not a problem, even in a game like XIII.
As for his tier placement or if he's "that" good, I've already stated that I put absolutely no faith in any tier list, nor do I or will I ever create one of my own because it's IMO, a waste of time. However, you seem to heavily underestimate him, from what it seems like because of your own personal experiences with him, which means either you're facing subpar Duos, or...and excuse my bluntness, you can't use him at all yourself.