Why would I wanna roleplay someone else's character?
I dunno, because it's fun? I loved playing as Commander Shepard, Revan or Geralt of Rivia.
Just for the sake of argument. In the originals, if you could play as Imoen - wouldn't you at least *try* that experience? Or as Sarevok? I would, and I would love it. It's not my *first* choice, but dismissing it outright is missing out, I think.
I'm guessing I'm a little older; but there was a time when it was pretty common for a DM to make up the characters in the campaign and you got to choose. Especially for newer players. Hells, the Starter Kit does this. Not everyone knows how to create a character that is fun, plays as you expect it to *and* is effective. Not everyone has the imagination to come up with something. So for them, it's actually pretty neat to pick something and just play.