Even if they gave me a month free, I doubt I would go back. I've been gone for a few years now and it just got to a point of grind for money or grind raids. It was boring and time consuming. Besides, none of my friends play and the guild I was in broke up shortly after I quit (some of the people in charge were dicks).
I did try to go back a few years ago, but being so far behind (started a new character on another server) and having no one to play with sucks. Tried to join another guild but no one ever wanted to play with me (because i was low level). I also just kept thinking that even if I do keep playing, I'll just reach that grind or raid point again and it totally turned me off.
I keep thinking I'd like to find another good mmorpg to play, but everything since has sucked ass and I still run into the same issues as I had with WoW. I think maybe I've outgrown MMORPGs...