I think people need to ask themselves why they are sending gifts. If it is because they want the recipients to enjoy them, or because they want to send them, then they should go ahead. If they want to be 'appreciated' and thanked, and will hold a grudge if this doesn't happen, however, then maybe they should hold back.
Like it or not (and on the whole I don't like it) many younger people don't feel the same obligation to thank others for gifts as we did. It's not personal, and it seems to me that when someone asks if it is worth bothering with family members who don't see things the way they do, then the answer is in the question, really.
Things have changed since we were young. People now marry and have children after years of living together, and many have far more than was average when we started out and were glad of presents of toasters and tea towels. They often don't need gifts of money either. Similarly, young parents often have two salaries and like to have fashionable items for their babies that weren't available in the past. They may also be very busy, with a new baby and a job, so don't have time to hand wash knitted items.
I know that's harsh, and I know that it feels lovely to have our time and care acknowledged when we make something for others. I knit, and know how much time and effort it takes. There is also the fact that many of us will have fond memories of older relations who made things for us, or gave us little gifts that we did appreciate, and it's natural for us to want to be thought of in the same affectionate way by our own families.
Nevertheless, I don't think it's reasonable to expect a new generation to behave the way we did on pain of being cut off. I feel the same when I see posts about people getting really upset over bits of card. I completely acknowledge their sadness, but it seems such a shame to let something like that come between them and their family members, particularly when the young people won't have any idea what they've done wrong.