Oh I enjoy the five mans too... I think it's just the sheer amount of them that we have to run for attunement purposes gets extremely overwhelming. I think if I didn't feel so much pressure to get everything done right now, and could sit back and take it at a more leisurely pace, I would enjoy them more.

I dunno about other classes being boring until 20. Some of them are, but some of them are really fun at that level (mages for instance are tons of fun at that level). Really it all probably comes down to personal taste. I just don't particularly enjoy playing one - at least as far as I can tell.