What temperature are dark beers (stouts and nut browns) supposed to be consumed at?
No, you're not crazy.  You have good taste.  The reason for drinking darker beer like stouts and porters is for the flavor.  If they are over-chilled, you lose most of that flavor.  Don't obsess over it, but in general a lot of people serve dark beer too cold.

That said, you should drink your beer at whatever temperature makes you happy. There is nothing wrong with a nice cold pilsner or Hefe-wizen on a hot day.