I believe this is part of the convenience of applications delivered in the cloud. (sorry to throw that term out there) It is part of the convenience that has me accepting fewer features in order to get that functionality.
There are companies out there who understand this, and are working hard to create a better user experience. Google for example went to great lengths in order to be able to update their entire browser in under 100 KB of download just to make the experience more efficient, user friendly and safer. Not only that but chrome updates happen automatically, again to help with security. It's very close to the experience I get by logging into gmail, which is always up to date. Now I can already hear rattles of complaint about "control" over your own machine, but I have to ignore this or I'll get completely derailed. I'll say in short that I think that control is an illusion, and the alternatives are worse.
If you have not already read this post by the chrome developers I highly recommend it.
And then you have the Apple, who has gone from a position of pushing hard to avoid needing to reset the operating system unless absolutely needed to requiring reboots for Quicktime, Safari and sometimes even iTunes (especially in windows). You can argue all you want that it's because of kernel extensions or who knows what else - but at the end of the day it doesn't matter why. This is bad design and leads to a diminished user experience.
Seriously what is so special about Safari that they require me to download 36.2 MB and restart my machine for a point release?? Maybe this didn't seem so offensive before Chrome, but now it feels dated and clunky.
I really should pick on Adobe here for the horror that is the Adobe Updater, but honestly I really do expect more from Apple. Adobe is too easy of a target.
Please fix this Apple, you can do better. Where is the Steve Jobs who wanted to save lives by reducing boot times??