Replacing the minion is at least somewhat understandable (because 95% of people want the mount anyway), although it got replaced by a pretty lame reward. Replacing the mount.. They obviously couldn't make a good reward by 3.55 for the minion. They definitely won't be able to make a good reward for the mount either, and that will really tick off all the current PvP players SE has currently gained their trust in after a really bad start to PvP.

That is why they're PvPing in the first place.

If SE can replace it with something meaningful and awesome, great. But we all know if they do, PvE players will just complain about wanting that next. SE can't really win, although they have in some sense because more players have been getting into PvP because of these rewards.

No player in this game is going to quit playing because the Hellhound is PvP exclusive, but the top/dedicated PvP players would sooner quit if their rewards and efforts are made pointless again. For the third time.