I think these dimensions are cool because they look more natural to me...and they fit my dresser perfectly.
Good luck with the tank, but I would strongly suggest NOT putting it on a dresser. As you probably know, it will weigh close to 600 pounds with water and rock, and that's just a risk I would not want to take with furniture that is not designed to hold the weight. I've had a 30 gallon long on a dresser before, and it started to make me nervous after a while... I ended up moving it to a stand later, and my dresser is now kind of damaged structurally as a result of the tank. One more thing.... have you thought about the distortion that would result from a convex tank? I'd think it would be crazy distorted.