DRGs who are not weaving their Jump skills into their combos are going to be doing significantly less DPS than one that is.

The only reasons you shouldn't use them are:
A) You know an AoE is coming up, and don't want to be caught in the air.
B) You need to refresh your DoTs/Heavy Thrust

Any DRG worth his salt should be using them.

Not that I'm the #1 DRG in the game, I'm not even close.
However, to maximize DPS (like you should be), you should be using your Jump skills.

The worst thing is seeing a lvl 50 DRG in i90 gear doing nothing but 1-2-3 (Full Thrust combo)