The post that started it all: http://blogs.msdn.com/kcwalina/archive/2005/03/15/396086.aspx
I even posted some feedback way back when: http://blogs.msdn.com/kcwalina/archive/2005/03/15/396086.aspx#399803
So, the big reason for it was “VB users would see TWO collection classes.“ IMO, thats a bad reason for a complete namespace change. Doesn't the VB Environment have an Intellisense that could filter that? Doesn't it already just magically import the “Microsoft.VisualBasic.GlobalFunctions“ or whatever?
Why couldn't the VB team take responsibility for that assertion, and make their own changes, instead of forcing the entire .NET targetting community to this bit of sillyness?
Ok fine, leave it then, but now move all the other “Concrete“ implementations to ObjectModel. but thats not gonna happen either, so JUST because of VB, we have 3 classes in their own namespace. Silly. Silly. Silly.
Various blog posts about it:
http://blogs.msdn.com/kcwalina/archive/2005/03/15/396086.aspx