We skipped sending them one year, because we only got maybe two one year, but the year after that, I swore out loud a few times and recommitted to sending cards, and now, no matter how many or how few we get, I send them.
You know another thing going down the toilet - the traditional Christmas Day phone calls. My wife's family, once they'd moved all around, used to spend half a day on the phone, calling each other, and passing the phone all around to everyone, so we could all wish everyone a merry Christmas.
Now we just get a crappy group text. That's no good!