Their forcing of the download manager app (painful trying to find an alternate download to upgrade Flash) should be a key reason for people to abandon the platform.
Nothing burns me up more than vendor-provided "download/update managers". I'll keep my app updated myself thank you very much. No, you don't actually need to run your program 24-7 when it's only used once every few months on my machine.
Just thinking about it makes my blood pressure rise.
(Yes, I know I can go back and uninstall the download manager, but now there are 2 of them - one specifically for IE/ActiveX and the one for Firefox that they recently created).