My main has done all the epic quest lines. Well, except Wildermore. I will probably finish that at some point, but I'm having a hard time getting excited about a zone I found faceroll easy with yet another follow-up grind to it. (I have no plans to grind rep there *shudders* even if I manage to finish the epic.)
That being said, my alts skip around the epics. A lot. I do parts of them - when I feel like it and when they line up with the area I'm questing in. Or the parts that lead to the legendary skills stuff.
It's up to you. Do the epics, skip the epics - it doesn't really matter for alts. I would recommend doing them all at least once, though. They are pretty cool.
Freeps: 85 mini - Adnia, 85 LM - Sariela
Creeps: Baldardash (WL), Rigmarole (warg)