No, the idea isn't to electrocute the victim. The whole point of it is to as far as possible give a non-lethal shock. If you're going to electrocute someone it would be easier to just shoot them with a conventional firearm.
The original meaning is a popular bit of trivia in today-I-learned circles right now, and it's historically interesting, but you should know it doesn't reflect common usage.
They're obviously not designed to cause death or serious injury so in this case saying tasers are designed to electrocute people is probably not appropriate (depending on how cynical you are about the western world's increasingly militarised police forces). It's far more accurate to say a taser is designed to deliver a "non-lethal electrical shock", and make a note of the absurdity of expecting non-medical personnel to consistently deliver painful electrical impulses to a person without killing them.
At any rate; the amount of energy the taser attempted to deliver was exactly the same as every other taser; however, due to the significantly decreased resistance of moist skin, the voltage drop across the body was a lot lower than the "normal person" the taser is designed to hurt therefore more energy made it to the victim's heart, thus killing him.
... This comment got a little more political than I expected. Sorry about that.
However, in a discussion about tasers of all things, I think it pays to use the more classically correct definition. Saying that a taser is designed to electrocute you but not kill you simply invites confusion.