Probably to maintain customer buy-in. Not sure about AOL, but the others are very pervasive & bu**ers to get rid of, in my exp. Ppl might well think, 'sod it can't get rid of it, so I'll stick with it'.
Never had bother with Nero, but never tried to remove Nero 7 so maybe thats different. Norton before they created the removal tool was a pain but is sorted now and AOL I've only removed a couple of times and have to say I found it fairly painless as well. Not completely painless as there were a couple of bits left over but not OTT. Regarding Norton, they were asked years ago, before the creation of the removal tool what the reason was for the differculty people had removing it. Their answer was that they specifically designed Norton to integrate itself into the OS fully to protect the system from viruses and this subsequently had the undesired effect of making it differcult to remove. Not saying the arguement they gave was true but when you think about it in that context it does make a kind of sense. However at the time I did wonder that if this was a true explanation of their reasoning then why did no other anti virus software exhibit the same problems. Make your own mind up time I think. Can't remember where I read it either as it was perhaps 4 or 5 years ago, it might even have been PCA who knows.
as when some unrealising victim installed one of the 337 trillion aol install cd's that are evenly spread around the planet, they found that their computer would not connect to them via a modem. I never did find out what 'tests' aol did on the phone, just that they used to tell the poor saps the their modem was stuffed, and to contact their computer vendor who should supply them with a new one for free. Enter me, who would sometimes spend weeks fielding call after call on this, only to tell people that it was aol, and to prove it I set them up with a test account into an isp (that would only really access the home page, nothing else) and let them connect and see for themselves that the computer would work as advertised, and if they insisted on using such a service then on their own heads be it.