The things that cause me to "character hop" are:

1) A new idea that I just have to try, or something I just have to find out about (e.g. cabal I've not been in, or something).

2) I log on the read a helpfile and a minotaur slot is there, so I take it while I can.

3) Dying in a fashion that disgusts me, at which point I need a break from the game for a while. This include things like being jointly ganked by two cabals that both outnumber you anyway when you are no powerhouse, and already have your item when they both for some reason attack your cabal when you are alone, to getting multi-killed by an air-offense form and full-looted every time you unghost if you are an orc. (The latter never happened to me but I've seen it done to others, and it is cheap imho.)

I still manage to have a few chars that I play for over 200 hours, but owing to factor 3, fewer than I once did.