No worries. I am very soon they will embrace bitcoin and perhaps integrate bitcoin in their latest windows??
Microsoft bundling a Bitcoin client with Windows would be very bad.
- It probably violates anti-trust laws, previously Microsoft got into a lot of trouble for including Internet Explorer with Windows.
- The client they ship with Windows may be backdoored/bugged/insecure.
- It's not good to have a single client that everybody uses.
They don't need to bundle bitcoin client with it, they could just add bitcoin to microsoft payments, which would be even a bigger thing.
There's no legal issues for them to add it to their own payment system, atleast not that i can think of.
Other points you listed i agree on, it's better for individual user to pick a wallet on their own, but doubt there's justified fear of backdors..