Why do people assume that if they
don't want to do the mission, that it's meant
to be skipped? The guy above spelled it out pretty clearly: it's extra content. It doesn't hurt you if you skip it but it rewards you if you do it when it's level appropriate.
How dumb do people have to be to complain that soloing a Hoth H4 at 50 doesn't give good loot?
The only problem with completing them is that there are too many low population servers, but that has nothing to do with Heroic 4s in and of themselves.