OF COURSE Blasters do more damage. Damage output is 100% of what they bring to the table. They're also glass cannons. You're not going to get extra survivability without sacrificing damage output. Sentinels are not and were never meant to be "tank mages".
Also, yes, unslotted is also skewing your impression. Slot your powers, geez.
Granted, DP is not the most damaging "blast" set, but it's still a decent set.