The problem isn't that the cubes are too tough in the slightest, they're easy as crap to kill. The problem is that there is ALWAYS one mouth breather that will drop a cube before the other two are even open to being shot at. At that point you're pretty much done as without an amazing team there is no way you'll fight off the flood of raptors and push out to open up the other cubes. Cure is thus uniquely able to be completely ****ed up by one dumbass. If some idiot pops a transformer early or lets a batch of probes slip by that sucks, but you can recover and keep going.

Cure though has NO margin for error, you do it perfectly or you die.

That's all well and good in some sort of fleet only organized raid, but when you open something up to a public queue your saying "we expect this to be reasonably doable with a random pick up team of less then optimal build and skill". The other two Spaces and by and large the grounds are such. Even a fairly bad team can muddle through without the optional, but if you get ONE idiot in cure... you're done, and that's just flat out not fun. I don't queue for it anymore simply because it's like playing the slots. Roll up a team with a clue and it might well be the easiest elite of all, but get one dumbass and enjoy wasting that hour long timer.