While you do have a a bit of a point, let me clarify something for you. Single target DPS maybe close, but what you are missind is the AOE abilities ALL other tanks have. This is where you see the DPS difference. While you CAN see warrior tanks produce some higher DPS numbers, you rarely see any of the other tanks that DON'T produce the numbers.
If Pally tanks have ability WXY&Z and Warriors have ability Y&Z, the two are not balanced. Where once it was justified because a pally tank could produce more DPS they also lacked the threat a warrior could produce. When threat became fairly easy to keep and pallies got a taunt like the warriors taunt, it was no longer balanced.
The only way to fix this is to either homogonize them further or give them back their specialization.
To homogonize the two would require the pally tanks to lose their AOE abilities or to greatly lessen the damage output of these abilities. The other option would be to turn shockwave into an AOE DoT effect, up the DPS of cleave and devastate.
To return the specialization they would have to mess with threat gen as a whole. THey'd need to pull the taunt from pallies and make shockwave a single target ability.
I don't agree with either of these extremes but would like to see Warrior DPS go up and threat to recieve a bit of a face lift.