But transmog didn't add replayability on the spot. I can only talk for myself, but I didn't grind out old instances back then, I mainly farmed one set of gear for like two or three weeks and was done.
Also catchup mechanics are nice, but still, they don't carry a patch. I raided firelands just before it came out and had no reason to enter the dungeons besides the lore.
8.3 came out January 14, I'm still doing my visions and assaults on my main.
When 4.3 was 3 months old I didn't do anything related to the patch in the game.