From what I could see, the only discipline use early on comes from the caltops, dodge and marked for death. Which are survival abilities. That use up half the demon hunters resource pool for not a lot of use.
Keep in mind. I haven't played yet, so this is conjecture based on watching video's, nothing more.
Caltrops - seems fairly useless, the snare didn't seem to do much at all.
Dodge - You get a hatred shot that dodges you back, which seems to get more play. Even without that shot though, this is not a damage skill.
Marked for death - Well + damage is cool and all, but very very few mobs live long enough to actually make it worthwhile to apply. This skill seems pretty limited in use. It would be better off as a group effect, like a paint grenade or something that made them take more damage or made them easier to hit. Could be really awesome later on though against very tough mobs/bosses.
So - my point is when you look at the demon hunter and it doesn't seem to do as much damage keep the following early on. Up to level 10, fully half of the Demon Hunter's resources are devoted to those three skills and not being used for damage. Whereas 100% of the other classes resources can be used for damage 100% of the time.
I haven't seen chakram being used so maybe that's where it starts to pan out for you and the damage comes into it.
Edit: could be the video's I've seen as well. I've noticed a big disparity between situational skill use (when/where they should be good) and the people using them.