I get your point and agree to it to an extend.
While one can argue that Rift is not a 1:1 copy of WoW (for the nitpickers in this thread), it copies enough mechanics and ideas to qualify as what is universally called a "WoW clone". Many games did and still do so and Rift is in no way innocent in this case.
It doesn't matter if game X before WoW already had feature Y implemented or if "WoW copied that from Eq!!", as nowadays the context is all about getting a piece of the 10mio+ cake.
The problem is that making a mmorpg today, you are sort of between a rock and a hard place. If you stray away too far from the WoW sketch, you alienate people who can't relate to what your game offers -as it does not fit to their mmorpg habits fostered for years. If on the other hand you stay too close, people will yell "WoW clone allover!" at your game and leave it at around 250k after a couple of month and far from the inital 1mio boxes sold rush. Both happened alot in the past. It happened to Rift as well when in the beginning rifts and invasions alienated the quest sheeps who whined on the forums until the main aspect of the game got nerved into oblivion, while at the same time players rightfully complained "We're not in Azeroth anymore -except we are at lvl 50". The game is generally estimated to hold 150k-250k subs for a reason.
Many players today are bored to death with WoW clones, while at the same time the market seems to be not ready for someting new off the beaten path.
I bet at the Trion HQ heads are smoking about how to boost small scale (group-)PvP without blatantly copying arenas.
As to the flying mounts: That is one thing i'm shure they won't copy...just because Telara's landmass is WAY too tiny to support it. Telara doesn't even have zeppelins or flying from A to B on fixed routes via gryphons.