I also prefer to send and receive paper cards. I like the act of writing people's names on them, signing them, addressing the envelope, picking out the matching return address label, etc.. I don't write anything in them besides the recipients' names and my own name. I don't send cards for other occasions (birthdays, other holidays--except for thank you cards) so this is my one time a year that I sit down and do this. I also use store-bought cards--often ones I've gotten free in the mail, unsolicited, from charities, or ones my mom had lying around that she wasn't using.
For all I know, most people chuck them in the trash as soon as they get them; but I feel like, theoretically, they have more "staying power" than ecards. I usually keep the paper cards I receive out as decoration for the holidays, then tuck them away in a box somewhere. If I had to switch to ecards for some reason, I don't think I would go to any more effort to personalize them than I do now, so the "event" would be over for me a lot faster, too (bad). I look forward to doing my Christmas cards starting early in the fall and I get them ready in advance so I can mail them out on December 1. I like seeing the neat stacks of envelopes sitting there. If there was some sort of outside reason why paper cards could NOT be sent any more, I have a feeling I would just stop sending cards at all, because ecards wouldn't be that much fun for me. At that point I would rather just send people an email and try to have an actual e-conversation with them.
I don't think I've ever gotten an ecard for Christmas myself... Well, maybe a couple of emails that had the holiday newsletter or photo attached. Those are fine, I just save the attachment to my computer and I guess that's one less bit of paper I have to file somewhere, but I tend to forget it ever happened more than I would with paper.