Comment by OkayPhysicist

MDMA is a lot more acutely dangerous than nicotine, and somewhat moreso than alcohol. If you drink too much, you'll vomit, and for the most part be fine. Obviously that not always true (I'm sure everyone knows at least one person who had to have their stomach pumped in college), but for the vast majority of users, their body's natural defense against being poisoned works fine.

An MDMA overdose, however, needs active, external cooling to ride out. We don't really have a natural safety valve for overconsumption.

That's not to say it should remain banned (I'm quite pro-legalization myself), but it's not entirely arbitrary to have MDMA banned versus other, less acutely dangerous drugs. Better examples of unjustifiably banned drugs are psychedelics such as LSD.