Seagazer, as your daughter used to prompt them to make cards for you I'm surprised they didn't carry on with at least a card as they got older and, presumably, organise their own cards (and indeed presents perhaps) for friends, parents, each other. You say they do give presents to their parents. Maybe you could find a tactful way to say something to your daughter, or to them, reminiscing about how you loved their cards when they were younger.
What my grandchildren do is to some extent a reflection of what their parents do. It also depends, I've realised, on their personality and, of course, age. I can understand that you're feeling hurt.
Indinana's post includes a lot of what I've said - sorry to repeat, only just saw it!