I think present buying is a bit of a chore, not knowing what to buy people. Yes, it's nice to give, and receive, but everyone has different tastes in clothes, perfume, home decor, etc. It's very difficult to get it right, even for a close family member, or friend.
Personally, I'm more than happy to receive flowers/chocolates, which I enjoy looking at, and eating ... and knowing that I've at least been thought of! I'd hate to think my son or daughter were stressing over what to buy, when they both have busy lives, and there's not anything that I really NEED, so it's often spending money just for the sake of it ... I'm grateful to receive anything. Although, admittedly, DD does put a lot of thought into her gifts, which is lovely, but I'm equally appreciative of the beautiful flowers from DS and DiL! It's the thought that counts.