I'd like to see this skill/art encouraged everywhere, especially with the younger generation. I have one almost-five grandchild who lives very nearby but, prompted by another thread here recently, I've begun to send her postcards whenever I see a great picture. She loves getting them and I hope she'll send some to me sometime soon.
Yes, I do think it's worth the time and effort to send a letter. They are personal and timeless and show you care. I've got a stash of letters written by my in-laws during their 1930s courting days and some from my late son which are, of course, truly precious. You can't really keep text messages can you?