I guess I never looked at it in the "just a dream" sense, and you're very right.
Spoiler:
Though Heroes is serialized and changing the past screws with a timeline that might be important to some (hopefully, anyone ascribing to the show would realize that time isn't a "line" as it were, and to look at each moment, or even point in time, as its own story, with its own changes), Hiro's plight to make things "right" (whatever that may be) is actually very interesting to me. After all, things may never be right. Though time-travel may seem to some as the all-powerful singular ability, changing the past has future consequences or may not even have the desired affect. Feeling impotent is a bitch, especially when you've spent years (as the future Hiro has) trying to fix the past, all to find only failure (thus far). After all, just about every power portrayed thus far has found pros and cons.
I think the baggage is interesting, and it's possible to parlay such baggage into its own element of the story.
Also, I'm going to warn of spoilers. I just realized that there's some spoilerage going on in here.