Official Blizzard Quote:
The runes have really just been renamed to allow us greater flexibility in what they do so we're not creating a weird detachment from what they're called and the effect they provide. For example what was the multi-strike rune going to do for ... say... slow time? And does that match what the name implies, or what you would assume? Probably not.
Also, personally, the newest names [...] are very much in the theme of the world and Diablo. Lethality/multistrike/power were very game-mechanic in approach, and even when they moved to viper/hydra/force they had an odd mysticism attached with them. Now they're very plainly named by interesting sounding materials. Great, very matter of fact and real in their theme, IMO.
Runes still have a general theme though, you'll know that this rune usually increases damage in some way, and this other one usually decreases cost in some way, and this one is a wild-card and usually changes how the skill works in some crazy way. But we have enough freedom now that multi-strike/hydra whatever you know it as, doesn't have this defined perception that it's always going to "multi-strike". Whatever that means to each player.
Soon enough, he replies with the current working names of some runes they're playing with at HQ:
(A big thanks to Nektu for the wake-up call :P)