McAfee (and Google toolbar/Chrome) are not critical to the functioning of Flash Player. These are optional installs and we do state this on the download page.
I understand how you feel. I've passed this along to our team and will continue to do so. The fact is that these offers help offset the development costs for Flash Player (which is provided for free). I hear your request to make this an opt in, instead of opt out, offer and I'll also make that clear to the team.
Please see the discussion on : http://forums.adobe.com/message/5242885#5242885