I always enjoyed events, to be honest. Yes, it was a bother to drive to GameStop. Yes, it's kinda evil since it's already in the code (not counting things like Spacial Rend/Roar of Time Darkrai
), but they were still fun since you got a special 'mon out of it. WiFi events are better and less evil since you aren't deliberately dragged out to a store that wants to sell you stuff and get to stay home. Short time frames and the one-time-only nature of the events are still a pain sometimes, though, and a surprisingly large number of people have no WiFi.
As far as Mega Stones go, I think Blazikenite (Couldn't we just have Blaze Meganite, Aura Meganite, etc.?) has a good chance of being unique. It's the only starter megalution shown so far, and I get the feeling that they added it "for fun", so to speak, as something to kick off the release.
...Then again, I could be completely wrong, and all starters have event-exclusive Mega Stones. xD That would suck. Really, many more Mega events would suck, but I expect the amount of event-only stones to be small. It surely can't be all of them, as has been shown.