Just stating things doesn't make them true. You don't work for Microsoft's VS team and therefore don't have any idea of the decisions that were taken or the reasons that were given. You're just blindly stating that it's easy.
If building a CRT is so easy, don't link against the Microsoft CRT and build your own. That'll allow you to use the VS2011 IDE with no compatibility problems on XP. That way when it goes wrong or is slow, it'll be your responsibility to sort out and Microsoft won't have to slip the release of VS2011 in order to test the CRT on XP, and everyone will be happy.
My point about XP mainstream support isn't that Microsoft are deliberately breaking support for XP, just that they are not required to support XP anymore. Consequently an argument that "Oh you must support XP because my customers use it" doesn't hold any water at Microsoft.
If you want to argue for XP support in the CRT, I would avoid using the "it's cheap and easy" or "you have to" style arguments. If it was cheap and easy they'd have done it. And they don't have to because XP is out of mainstream support.