1.) Not every "high-movement" fight is the same. Your argument is again based on generalization.
2.) Not every type of survivability is the same. Check why warlock survivability is better there than mage. Again, generalization.
3.) See, you seem to get it, warlocks seem to have better stuff in this specific raid tier. Ain't hard to deduct. Yet, when you look at actual stats they are still below 10% in variance.
Every. single. tier. has top dogs. This is nothing new ever since vanilla. But unlike most of WoW's lifetime, specs are more balanced now then ever. This does not mean that they perform the same. This means that every spec has a chance to step into an encounter and pull his weight. Maybe next tier we'll have mage being the number one class. Depends on the encounters, not the class.
Don't be salty cuz your spec is not the best at everything. It really doesn't matter.