I assume you mean any other horde race, since of course night elves can be druids over on the alliance side. But moreso than any other class, it makes sense to restrict druid to the current races. There's a lot of deep lore behind the fact that only tauren and night elves an be druids. It'd take something pretty special for gnomes or trolls to suddenly gain the ability to morph into animal form, don't ya think? And as far as I know Blizz has never opened up ANY class to new races...it'd be much more logical for trolls to suddenly gain the ability to be paladins, or gnomes to be priests, than for any other class to be able to roll druid.
Having the new DK class open to all races is one thing, but remember it's a "hero" class not a regular class, and there's lore support there because all the classes can satisfy the primary pre-requisite of becoming a death night: they can die.
P.S. I'm not the type who really minds the word 'drood' or even 'dr00d' instead of druid (even though imho both are lame since they don't save you any characters) but this is the first time I've ever seen 'drd' and it's both immediately and extremely annoying. Drd would be pronounced either "dee ar dee" or "derd". With all due respect, please stop.
Edited so I could say "What are you talking about? I never said trolls can be rogues!"
Edited, Sep 29th 2008 6:16pm by JeeBar