MoP being the most fun era of lock, not from my perspective
Besides what you're saying is that locks aren't tanky, but they are and justifying 1 lock vs 4-6 melee jumping us in a bg as no tankiness is a poor choice of evaluation though.
In most cases 1 form of escape is not nearly enough to truly open a gap between you and most melee these days and the thing is people talk as if blizz gave us one extra tool of escape, circle has been in the talents since prepatch yet no one chose it over dark pact for a reason and that is because 1 escape is not nearly enough right now.
The fact that blizz is moving the talent to another tier does not mean we'll get extra mobility with the same tankiness, they're basically depriving the choice of tankiness vs mobility and simply saying this is your only choice , which is bad in general because at this stage of the game 2x tankiness talents > 1 tankiness + 1 mobility talent so it is an effective nerf to locks in pvp.
What they should've done is given demon skin as baseline talent to further reinforce the tankiness model and added a slow in the CC tier so that we can finally choose an actual CC.
For example of possible new talents in CC tier , Affliction : corruption now slows the target for 50% for 8 secs, destro: conflag now snares the target for 50% lasts 8 secs, demo : your call dreadstalkers snare the target for 50% over 8 secs. etc.
And thus you'll be able to choose which CC you want in the tier, instead of being forced to go demon skin and no other choice or demonic circle and still no other possible choice.
^ this is better design than "circle and demon skin have swapped places ".