Whilst you're right to compare 51 Inq & 51 Pyro - they should be doing similar DPS, and afaik that's more or less true - mages have hybrid specs that net higher ranged DPS on any fight that isn't melee friendly or requires movement. Clerics are pigeonholed into 51 Inq for ranged DPS, and frankly it would be nice to be able to develop a ranged hybrid that's somewhat more complex, and consequently offers higher ranged DPS at the cost of greater penalties for making mistakes.if you play inqui in all fight, you are doing it wrong, do you think mage play pyro in all fight and whine that mage can't dps? no, they plays 38/28 in itzuziel for example.
Stop whine, and go train your spec in the dummy.
That's what is currently good about mage dps:
You can 51 Pyro for viable DPS with an easy rotation that is only mildly punishing if you mess up.
You can PyroLock for more competitive DPS with a slightly harder rotation that is more punishing if you mess up.
You can Defilemancer for top end DPS with a yet harder rotation that is extremely punishing if you mess up, and doesn't support a lot of movement.
For Cleric DPS:
You can 51 Inq, 51 Druid or 51 Sham for viable DPS with insanely easy rotations that are barely punishing at all if you mess up.
You can J'n'B for competitive/top end DPS with a slightly harder rotation that is more punishing if you mess up, and doesn't support movement.
That's it - a bunch of 51pt derp-easy builds and an oddball melee range casting hybrid that you can only get the best out of on fights with minimal movement.