My stable of alts keeps growing; the only class I don't have yet is the scourge warlock and I'm planning to create one soon. It's funny to me that I sufficiently enjoy creating alts in this game to do this even though it's not very alt-friendly if you think about it.
Sure, having a lot of alts can be beneficial when it comes to farming certain currencies that are capped per character per day, but getting an alt up to a useful level requires a serious investment of time or money, considering the grind required to get all your boons alone.
Also, the levelling process is highly repetitive: I think the game does a good job at easing new players into new features and mechanics, but when you're on your 7th alt it gets very old to have to go through all the various tutorials about companions, invoking and what not. I wonder if the tomes of experience enable you to just skip some of that stuff? Might have to try that next time.
But while you can do some AFK-levelling via invoking for example to skip zones you are tired of, there aren't really any "active" alternatives to levelling via questing, as activities like dungeons or skirmishes only grant piddly amounts of XP. So where in other MMOs, rolling an alt is an opportunity to see a different starting zone and try a different levelling path, in Neverwinter it's pretty much always the same old.