These kinds of random deaths do happen on MDMA, & have often happened over the years. When I first became interested in raving & MDMA I investigated the deaths, which up to that point numbered only a few dozen at most. I came to the assumption that two processes were leading to death on MDMA.
1) A single, idiosyncratic allergic reaction, much like Toxic Shock Syndrome. Notice that the syndrome can cause dangerously elevated body temperature!
http://en.wikipedia.org/wiki/Toxic_shock
2) Heatstroke related DIC, or Disseminated Intravascular Coagulation. Notice that DIC can result in Multiple Organ Failure.
http://en.wikipedia.org/wiki/Disseminated_intravascular_coagulation
The first cause appeared to me to be extremely rare. A death from a severe allergic reation to MDMA appeared to occur when use of the drug wasn't related to raving, or when a very small (say a half pill) dose was involved. This also tends to occur when the user is taking MDMA for the first time.
The second is obvious & has been discussed at length here & in the media.
Many years later I had cause to consider Water Intoxication as a cause of death on MDMA, for obvious reasons.
I now consider a third possibility. I believe young people who are unprepared for the effects of MDMA, those who take a larger than expected dose or who get freaked out for any reason are also likely to suffer an adverse reaction to the drug. I suspect that a serious freak out or panic attack could cause a dangerous rise in blood pressure, which of course is already raised by the drug. Sudden, heavy increases in blood pressure can have pretty dire results & this itself can lead to DIC & other heatsroke related illness.
I consider that it's possible that all MDMA-like drugs are capable of causing death through similar action, though I must stress that I am no a medical professional & am merely making assumptions where I cannot find definitive proof of something.