To answer a question from a previous thread, diablo 3 on inferno mode will be damn hard. It doesn't need to cater for kids and casuals because it's rated M for mature and 15+ in UK. So if players bitch it's too easy on inferno they actually have an excuse to say it's not for kids.
Wow is for all ages and MoP will bring a lot more under 12s into the game. So it needs to be made casual and clearable by them, which is another reason for LFR. So if you are mature and have a brain then u probably not enjoying current wow like you did in burning crusade, but trust me diablo 3 will keep you entertained.