Users view updates from Apple as risky.
Here is what one can expect with an update to iTunes:
-four or five "yes I agree" click-throughs, one for each service the user hasn't signed up for or ever used
-longer load time and general bloat
-random UI changes that make it an exercise in "what will they think of next" to do basic stuff like sync a phone
-an army of snotty "senior" "helpers" explaining the problem is not a problem, most of whom just don't bother to read
-a SECOND set of random UI changes and feature removals for media organizing, moving or removing stuff like menus and ability to manage play lists, some of which represents hours and hours of tinkering with it.
-"Careful, don't do that" advice from people who lost their whole library, or had to reinstall and couldn't find the library on the hard drive again.
For Quicktime, it's about the same, only the user doesn't use the program much beyond obscure or old porn
Apple has a BIG PROBLEM trying to push their UI bullshit into an environment where their UI bullshit stands out as particularly retarded. There's NO FUCKING REASON to remove the standard word based drop down across the top of the program. More space? People already have more screen space (or second, or third screens) than they know what to deal with. Doesn't look good to emo-fags? How about a toggle to turn it off? (which leaves it on by default)
The actual risks for a slight chance for a security exploit are meaningless compared to the guaranteed fist-smashing-keyboard frustration of a simple update. I have actually helped users disable updates from Apple because they were so afraid of said bullshit or their old iPod or iPhone suddenly not working with it.
If Apple wants to get people to update on Windows, they need to stay within the expected design parameters of Windows better and just let the program look different on different platforms.