What I see with App Store sandboxing is a way to allow people to more easily try and buy apps without worrying what those apps are doing to their computer. I'm very careful about downloading and trying apps on my Mac because I don't know what files they're going to leave around on my computer or worse. Sandboxing in the App Store is a great way to make that situation better.
The last thing I've seen is transparently compressed files; not exactly exciting. I think we hit the peak around the leopard-snow leopard range.
What does that have to do with my point? He said Mac is already becoming more restricted "like a appliance". I said that that hasn't been the case for the last 10 years of OS X and is not the case even now. The only counter-example that comes to mind is the removal of the Input Manager haxie capability (a GOOD thing).
TL;DR: You argue about what "might happen in the future", while I replied to someone complaining about something that happened already.
P.S Who uses "dude"? A 15-year old?