JUST BECAUSE THEY WORK TOP DOESN'T MAKE MY STATEMENT ANY LESS SOLID...
are all and have been 100% COMPLETE SUPPORTS.
These two statements are incompatible. Quite a few of the champions you mentioned aren't dedicated supports. Lulu, Annie, Karma, Morg, Nunu, and Zilean have all seen play in lanes besides support. Just because these champions work as supports doesn't mean they are only supports.
Bard has unique and interesting abilities. Two of them wouldn't work well with damage purchases. He also needs to roam a lot, which makes having him as a laner a bad idea. That's fine. It's a unique design that hasn't been done before. Screwing around with a good thing to try and force role diversity isn't necessary.