Nothing wrong with stopping for a while. I quit for a while and missed most of Cata and Pandaria but it was fun to come back because I was actually interested in what was going on. If you think you won't be interested in the expansion just wait and play it later.
This is exactly what I did. Quit in early Cataclysm and recently resubbed on a shiny new account last week.
So far it's been pretty enjoyable, if not a little overwhelming. The raiding (which I've only read about) has me scratching my head a bit. The revamped 1-60 leveling is new content for me and overhauled instances like RFC, BFD, and SM keep things fresh. Still not sure if I'll end up buying Warlords though. Leaning towards yes right now, but we'll see once I have to trudge my way through Outland.