I'm a proponent of trimming the LFD q's, as I feel it's 4x harder for MDPS or Ranged who want DPS roles, get in a group and it falls apart after the first pull.
But, at the same time there are some simple facts to consider.
1 - Roll a class that can tank ... THEN LEARN TO TANK ( don't just roll in PROT and Q Heroics )
2 - Join a lvl guild or RAID Guild and chain heroics that way
3 - Broadcast in chat LF Tank ( maybe even throw some gold ) to make a group
4 - Make friends and Q up on your server forums
5 - Accept the fact you're going to wait 30+ minutes for a random.
Point being, there are 3 easy ways to speed up your Q times. 1 Hard way and 1 way that makes you accept the way it is.
In terms of why there aren't more tanks, as someone above said, right now it's not faceroll. I still get pugs who have never seen a fight. I will admit that I thank god for guild repair, but at the same time it makes a success pug all the more enjoyable ( like a sense of accomplishment ). Right now, gear doesn't allow for it and requires skill and competence by all party members.
As for the hybrid, in the end it may not matter. A shi*ty tank is a shi*ty tank. Just because the gorilla can tank a boss, doesn't mean that adding more of them will solve it.
Yes, the wait time would decrease, but the fact that they may pull, suck and leave won't go away. Now you have to wait for another tank to Q and hope he's got a head on his shoulders. Rinse and repeat.