There's an old saying "If you want to HAVE a friend, you have to BE a friend" and I think this is very true. The genuine friends are the ones who make the effort to keep in touch, remember little things like anniversaries, special events, give you a friendly phone call or e-mail when you're feeling down or unwell.
People lead such busy lives these days but you never know when you're going to need your friends, and if you don't make the effort in the good times, why should they make the effort in the bad ones? I don't think it really matters which methods people use. Some people will feel more at home using technology which suits their busy lives; others prefer hand written cards. The important thing is that people remember and care.