Honestly, I have no idea if the MP SRK is 2 hit or not. I'd like to know that for sure myself. I know the LP SRK is still definitely 1 hit and people can still use it to FADC into both Ultras. But of course we'll all just flock to MP SRK if it's still one hit or can be FADC'd after the 2nd hit if that's what it is now.
I think they wanted to rebalance his fierce SRK. Without FADC that'll reduce the damage from his SRK, FADC, Ultra set up since you'll have to use a weaker SRK. But his fierce SRK can armor break now, which is a small plus.
Spider, you pretty much have the right idea. Fierce SRK for damage and anti air. LP SRK for punishing loose block strings and I guess to allow you to keep pressuring your opponent because fierce SRK will allow your opponents to quick stand before you can get in there face again.