I'm unsure about this change to be honest.
From my perspective, I personally think that we're (priests) the weakest class in the game for arena healing when it comes to viable escape routes (We have fear, which against our main weakness, and the majority of classes due to trinket is useless,) and this only makes us weaker with people being able to trinket out of mind control, which of course removes all viable CC we have when it comes to arena (during the first phase, and used as a defensive spell.) On the other hand though, we can now trinket out of hamstring, so I guess it could be worse (Poisons being no problem to me)
Also, this is a huge buff to the strongest class in PVP in my opinion. now warriors generally don't have to care about anything stopping them in any form for the first trinket cooldown
Gnome Warriors, Dwarf Paladins, Dwarf Priests, and Undead Priests get the biggest boost out of this, mainly due to their racial back-ups.
Rogues, Warlocks, and Druids will feel a sting though.