As long as it's just the new stuff.. I can totally understand any software dev (even filfthy rich ones like Blizzard) wanting to drop support for old ass shit like ME, XP, Vista. 7 though they should keep supporting, it's still way too widespread (I have 10 already).
I wouldn't have put it past blizzard if they had suddenly decided they need to force some patch on everyone who plays their old games though .