Why is Heroes so awesome? Warning-Spoilers!

[Alex]

Hiro's time traveling, while cool, is my most likely candidate for "what will eventually ruin the show."

While it makes anything possible, it also means that if ever backed into a corner it will be easy to use the equivalent of "and it was all a dream" to go back and do it again.

Impactful time travel is full of paradoxes and eventually will
accumulate enough baggage to be a serious problem.