In their other games you name characters, which you know will be permanent (except in WoW, in which case you get paid renames). Here you're naming an account that doesn't even have to be unique. And there wasn't really a prior warning when naming your account.
By the second explosion, most of the clowns had already fled the scene
People are whining over only being able to make one account per CD-key, which is different from every battle.net game to-date, excluding WoW.
Didn't bother me, and I thought the warning on the main screen saying you can only make one account was pretty obvious, but I can understand how someone who made a bad name or typo by mistake now has no recourse.