Theoretically you shouldn't need to restart OS X with updates to programs since they're supposed to be in their own sandbox. So if you install an update to it, then you should be able to quit the app and restart it and be just fine.
I do understand wanting to restart the system if the update requires modification to the app on the root level of the OS. Without really know what's changed in the app, you can't say whether it's poor coding on Apple's part, or a needed reboot.
I think it's fine.. yes you have to restart, but it tells you before you install the update, so I don't feel it's a big deal.