It didn't used to be like that. Not too long ago, I discovered a map of the Magic Kingdom (circa 1988 or '89), which translated some, though not all, of the names of the rides, restaurants, etc., into German:
And on eBay, I've discovered a German-language guidebook for Disneyland, circa 1981, which I'm assuming also translates names into German. I say "assume", because the auction only shows the cover; nothing on the inside, and I'm not going to spend $30+ just to find out. In any case, here's the cover: