I used to hate them but I've since gotten used to scaping and using them. I'd realistically take a 29 over a 20 long if I could only have one or the other. Fish benefit from the height, length and width are nice and all, but the height helps fish get away from aggression the most in my experience. Pairs of cichlids will go as far as they need to to chase away intruders, but for some reason they won't go up. I can have a colony of some small cichlid in a 29 just fine, but the same fish will start taking damage in a 33 or a 20 long. Sure it's a pain to clean them or reach into them and all, but whatever's better for the fish.
I also agree that taller variants of tanks make better displays.