Strange decision. Unless you follow my (somewhat paranoid) thinking that UEFA want to bury the FA Cup Final once and for all.
Apparently the final this year is the biggest money spinner UEFA have ever had, by some distance, so they're sending it there again, on the pretence that it is about the FA's 150th anniversary, and definitely not about absolutely coining it in again.
I'm a bit disappointed, really, though. I'd have preferred a trip to the Nou Camp or somewhere to see Eck's boys lift the big cup again, but a home draw isn't too bad