There have been a number of studies conducted about the health impact of MDMA. In monkeys, it has been shown to leave behind long-term brain damage, serotonin receptor damage for at least 7 years, etc.
Personally, back at University I had some acquaintances who got quite addicted to them and appeared to suffer the mental side-effects. It was really rough.
They are not safe. What they are:
* A potent drug
* Gives you a pretty sweet high (at a big enough dosage)
* Addictive (the addictive qualities of amphetamines has been known for decades)
Oxycontin, anyone?
Truly, I hope that these drugs are studied and science finds out which of these generally "taboo" drugs have great medicinal utility for certain ailments.
However calling these "super safe" is just like calling Oxycontin "super safe". It's a really bad take IMHO.