[natesm]

This has already sort of happened. Apps are forced to have some sort of permanent presence now. In the past, you could be running many of these and still have a clean menu bar. Now, you have to have an icon for Growl, an icon for Quicksilver...

[ricg]

Sure, but that's not restricting functionality. Sandboxing on the other hand will simply mean that those apps won't get into the App Store in the first place.

[natesm]

Well, it restricts my ability to have a clean menu bar. Honestly, it's the reason I haven't installed Growl from the MAS.