Yikes! Sounds like you really enjoy Christmas shopping whereas your next generation does not.
Personally, I think giving 5 presents to each child and spouse (when both couples are obviously making lots of money) is too much, especially when 4 of the gifts are under $20. It makes for too much "stuff" after they are already able to purchase all the "stuff" they specifically want for themselves. It may make you feel good, but chances are it doesn't make them feel good. That's why I don't see the point of it. If it were me, I'd try to give each adult a meaningful gift that cost a bit more -- perhaps a handmade ornament or quilt for each adult.
I also personally think that grandparents giving each child 3 Christmas gifts is fine.
Our family eventually went the name-drawing route, which was a great relief to everyone. But, this was a much larger family than yours (3 brothers and sisters, about a dozen nieces and nephews -- you get the picture). After quite a few years of doing it this way, the big family get-together at Christmas died out. The family split up a bit, and parts of it get together, but I simply meet with two of my siblings and exchange gifts with them at Christmas time. My adult daughter is not married and does not have children; she and her boyfriend are of the belief that the more presents they get, the better! However, neither is a doctor and both live on very limited incomes (and are in college off and on). Totally different situation than yours.
Maybe you could compromise. Gifts they give to you could need to be the things you want; in exchange, you give only one gift to each adult child. They can do the name drawing amongst themselves.
