Friendship does not come easy. You have to invest in your friends with your time and with your heart. I think it is selfish to expect others consider you a close friend when you don't even have time for them. Sending one sentence messages time to time for 'just saying hi', does not make you closer to anyone. How are you supposed to know what is going on in your friends life if you don't connect with them. You get closer to people in crises, whether it is yours or theirs, and in order to know if someone is going through a rough time in their life, you should be in contact with them.
God knows that I have so many overdue emails myself because I have so many friends away from me and piles of messages that I have to write. I don't persist to keep in touch if the other person doesn't try either but at least I don't expect anything from them either.