Thank you mamas for your advice/opinions. I appreciate them all, even though what Joe's mom and Krystine said spoke to me the most. I've been offering her sips of water from my cup a couple times during the day. She likes it despite not actually drinking much.
In the OP I was saying I didn't see the REAL need. I can see when DD nurses shortly after a solid meal, she usu. nurses for a very short time, and I assume she wants only the foremilk to ease her thirst. It is fine with me and gives her some extra calories (she's small) and other good stuff from BM.
But I agree that it's fun and is a whole new experience/activity for DD, and that I should at least offer and let her decide whether she needs to actually take in any.