There's something about the physical cards which encouraged me to send every year for Christmas. I personally don't like sending e-cards because I can easily deleted it anytime and may have forgotten whoever sent me a greeting in the first place.
The point is that as a receiver, to receive a card is like receiving a part of a person physically through his/her handwriting, scent or whatsoever. I love receiving them because it's like having your close friends/families being with you physically in comparison to e-cards.
It's so fun to do so!