The old Microsoft (when they were much more successful) adapted their operating systems to make it easy for people to transition from the old OS to the new. The new MS, like you, takes the opposite attitude: arrogantly assuming that it is everybody else's job to work around MS.
Lovefilm and Sky (and indeed the UK Parliament site) might legitimately wonder why they should have to rewrite their websites, which they wrote in good faith in a programming language that MS was supposedly committed to, so that they are compatible with an operating system that hardly anybody has bought.
You also forget that I have a third choice to complaining to MS or complaining to a third party: I don't complain at all and simply buy something else. That's how markets work.
I really hope you don't work for MS, for their sake!