Yes.
Paying for our meal means we don't have to duck out to get our dinner in the middle of your wedding reception. We've probably been working for 8-10 hours thus far and we need to eat something, we're only human. Venues generally place a table for us somewhere in the corner where we can observe the room and identify when key moments are happening that should be photographed. Most venues have a cheaper "cooked service meal" which we're fine with.