As everyone understood, the change is meant to avoid pet switching, for refreshed pet cooldowns, in arenas. Now, thinking that anyone who doesn't play pvp won't really notice any change, is just dumb.
I rarely pvp nowadays, but dismiss pet is a spell that I, just like most other hunters, use a lot more than it seems like some guys at blizzard think we do..
biggest annoyance, would definitely be in challenge modes. There are a lot of situations where you have no other choice than dismissing your pet, increasing the cast time by 50% will be a bigger annoyance than some people would admit.
Would be cool if they could just prevent hunters from being able to summon any other pet than that they start an arena match with.
(yeees, that extra second whenever I want out of a combat so that I can mount up, pop an invis potion, FD before boss slaps me, will annoy the crap outta me. If it won't annoy you, congrats.)