I am of the "younger generation" and I always send thank you notes!! Even for the littlest things, my family puts great importance on that sort of thing, plus its nice to know that your gift was received and appreciated! I send thank you notes for birthday gifts and cards, christmas gifts, having me over for dinner/to stay, everything! I have friends who do the same thing as well. I think it really depends on how you were raised, I hope that people are not thinking that this is the "thing" for my generation.