Why is Windows so bad?

I use Ubuntu for my main machine and have for a few years. Whenever I have to do anything with Windows - helping my gf set something up or get a game running or something - I am shocked at how bad the experience is. Constant pop-ups and advertisements for Microsoft services. Neverending McAfee ads. The user experience is just so bad. It sucks that you can't pay more for a version that isn't the Spirit/Ryan Airlines equivalent of an operating system.