Remember the three rules of Fight Club? 'We don't talk about fight club' .. WoW has those other servers we don't talk about .. Question is why do people still play on those other servers?
In a nutshell it has to do with FUN! As an example here is a clip from live with corruption in its glory:
To some people what you see in that clip is fun, to others the simple fact that is possible annihilates any possibility of fun!
And this brings me back to the topic of classic, I have a sub, actually more than one sub and play classic. I also play on those 'other servers' .. Why? I actually have fun on the other servers. They are full, raids are more fun, and PvP is a million times better. Live servers have turned into world buff addicts who do 2xmin clears and raid log. BG's are a sh*t show as they are 99.99% of the time one sided ..
Are you having fun?