The issue is not the PC being too stronk but simply that tragedies require well developed characters and the characters players build aren't well developed.
I think the bigger issue is that devs don't consider how mechanics affect narrative in a video game. If you do consider that, then you can construct any narrative you want. You don't have to define the character, because the player will define the character in their own head. You just need to give reasonable options and a smart player will accept them and follow along. Again, one of the biggest problems with Bioware games is that the options aren't reasonable. They're usually completely divorced from the game mechanics, and it makes no sense.
Can you elaborate? Bioware choices these days are divorced from the game in several ways - the availability of choices has little or nothing to do with your character's stats, skills or previous demeanor, their impact on the gameworld is purely scripted or negligible, and they have no long-term impact on the player character's standing in the world. As a result, they're basically aesthetic. I do think it would be cool if decisions had actual strategic significance, so you'd have to weigh doing the right thing against your party's wellbeing and your ability to successfully complete other tasks in the future.
That said, I don't see how that sort of thing would be a magic bullet in terms of personal narrative, which I think tragedy necessarily is. At the bare minimum, you can't have a tragedy unless you have a character who actually cares about something. And if the players are given free rein over who their characters are, then at any time they can basically decide, "oh, I don't think my character cares that everyone he ever knew was captured by nazi aliens and taken to their fascist sausage factories to be turned to mincemeat. I'm going to go do random subquests." Of course some people will go along with a narrative when they see it, but I think CRPGs players in specific are predisposed towards going the opposite way just to see what will happen. I know I do that a lot, even when it hurts my immershun and actual enjoyment of the game.
When it comes to choice and consequence in CRPGs, people generally measure its success by the impact the PC can have on the world, along the lines of how you can choose who is left in charge of Junktown in Fallout. The thing is, these choices don't actually impact your character as a person in any way (unless you're heavily into LARPing), and I know I personally didn't care very much, so in practice, the PC is left as this sociopathic, vaguely obsessive-compulsive superhuman cleptomaniac who arbitrarily chooses what happens to the places he visits while he's busy killing and stealing stuff. To get an actual personal narrative out of this, you need fixed characters with pre-scripted reactions that develop as the narrative progresses. That, or some kind of mechanic for character personality development, which is a programming and scripting nightmare and would almost inevitably end up laughably buggy or just plain silly. To do this well wouldn't be just hard, it would require some kind of fundamental design shift in a CRPG.