Don't forget rogue Evasion duels! My Shiv spam will be sorely missed there too.

I'm also not really concerned about Crippling going down to 50%. After playing a Ret pally and DK, you realize that's still plenty to keep mobs in range. Don't forget, we're getting or keeping other abilities to deal with kiting in MoP.

Looking at the talent calculator, there's one on almost every tier:

Nightstalker (20% speed while stealthed)
Deadly Throw (50% ranged snare/interrupt + damage)
Any of the level 60 tier (though Prep will have a less consistent effect on your uptime)
Deadly Brew (apply Crippling when you apply a non-lethal poison)
Paralytic Poison (random stun at 5th stack)
Shuriken Toss (ranged CP generator - good to use with Deadly Throw)

I'm not too worried about lacking the ability to stay on-target. More importantly, this is the opposite of "dumbing it down". Instead of getting huge passive benefits like 70% snares and 20% increased movement speed, you actually have to press buttons more buttons to stay on target in the new system. If anything, this is an increase in the skill cap.

I know we have other tools for mobility/snaring, but the thing is, we're still taking a net loss. We've had all of those tools before; the only new thing is Paralytic Poison, and if we take that, we can't use Crippling Poison. You mention that the level 60 tier gives us mobility tools, but remember that Subtlety already has two of the three talents, so we're going to lose either Prep or ShS.

So in the end, we get a little bit more ease at using Deadly Throw what with Shuriken Toss (although both of them are only a 30 yard range and most of the other ranged snares are 35 or 40, so it would still be possible for someone to keep us slowed without us being able to attack them), and we lose Prep or ShS (or both, if you take Burst of Speed, but then you gain that). Paralytic Poisons's not going to be very useful in a kiting situation, because you have to be able to reach 5 stacks for it to do anything, and if you can't hit the other person, it's worthless, whereas if you hit them only once or twice Crippling is immediately beneficial. The only real gain in mobility that I see is that Cloak of Shadows is now on Preparation as well, which is huge, but once again, you're still losing out on ShS.

I'm not saying rogues are getting nerfed into the ground or that we'll all of a sudden be terrible in PVP; I think we'll still be a force to be reckoned with. But there's no denying that we're getting a slight-to-moderate nerf in terms of mobility and snares (two sides of the same coin, one just affects us and the other, our enemy).

I have to say, I don't know ANY rogues who don't have shiv on their bar...of course I live in PVP, perhaps that's why?