I personally agree and disagree with you, probably because I've never played WoW.
Some of the new mobs I find to be very appealing like the ostards now being raptors, but some like the new dragons are sooo massive they can get in the way.
What I would love to of seen when the new patch came out was a mix of old and new. This way if a player likes the old version they can stick with it, or if they like the new patched version. Also would create more room to have new "custom" mobs using old or new skins.