I think Microsoft's shift towards security is long due and has very little to do with 9/11. I mean look at the MS code base that has been getting worse and worse if they don't act now and start securing it then it is going to continue getting worse.
What important features do you need? If you just want 'features' all your going to get is forced ideas, things just for the sake of it. Really good ideas present themselves. And performance is always important but I don't think they have shifted away from performance or at least not that I've seen any evidence of.
The fact that America is on a security crack down and then Microsoft does the same is purely coincidence. Microsoft would have had to switch to security sooner or later and I have never heard it suggested that these 'terrorists' are going to attack using people’s home computers.