Well, first off.. nobody has to "ditch" a character... so stop exaggerating.
A person either wants to re-experience a class story, or they don't. Replaying a capped level player through the class story is zero thrill and zero challenge. So all those folks you just rationalized for..... try again. It's nobodies fault but their own that they space_barred or rushed through content.
It makes sense. It's not about the challenge, it's about experiencing the storyline. Imagine if you had friends that were already lvl 50 when you started out. That's what happened to me. They were constantly bugging me to lvl faster so we could do ops together but I wanted to try different characters and record my story (with fraps). So I ended up making a bunch of characters but I tried to lvl faster anyway and got burnt out and ended up quitting.
My friends got bored and quit too. Now I'm back to finish my storylines but we never got to quest together. Now, that's just my case and I don't need a story reset cause I have new alts BUT I bet a lot of players space-barred through or were under pressure to lvl faster when they started out, which is why an option to replay the story would be cool.
And it's been brought up many times in the forums already, it's not like there isn't any demand for it. Implementing a quest "reset" doesn't seem all that complicated so I think it'd be worth it. Plus it would add "extra" content at almost no work for Bioware.