McAfee has been junk for years, and it regularly comes bundled with new pcs, pre installed "for your convenience". Obviously McAfee pays for the privilege of being pre installed, in the hope that the ignorant/ stupid extend their "free" period.
Un installing it leaves junk all over your hdd, and active programs still installed.
McAfee antivirus is a skanky ho.
As to programs on Linux, if you build it, they will come.
"It" is market share. OS X didn't have market share for years, but now that it's building, software is being developed for it, and the same will happen to Linux.
Steam is already there, and porting games to Linux. Now the users will come, and eventually, the stupid users will come, and then exploits and virus' s will come, and eventually mcafee will come.
Given that mcafee software is so bad, they're actively developing software for new markets.
Also, don't discount the "think about the children!!!!" effect, and parents panicking about their children's safety. Irrational emotional advertising is targeting exactly the protective instincts of parents.