The challenge used to be in making the effort to remember birthdays. Earlier, you had to make a note of it in a diary or embed it in memory. And you only reserved this privilege for the important few. Now, people know it’s your birthday because Facebook tells them. You can write a wish without having to look at the date. Coz, hey, Facebook will prompt you next year as well. With minimal effort, you can hammer out a few words and then get on with checking someone’s vacation photos, or comment on someone’s status.
Here's Absolute Lee on Facebook birthday wishes (and the changing nature of birthday-wishing in general). I once wrote a rant on the subject too. This year I went to Settings a few days before my b-day and changed the date, to avoid a repeat of last year's creepy outpouring of good wishes, mostly from people I don't know. (Since I use Facebook mostly to link to my writings/spread info about the books and not for personal stuff, I accept friend requests from pretty much anyone.) As I've grown older and greyer I've become a little more tolerant of birthday wishes in general, but I draw the line at being wished in a manner that reminds me of the spam ads in my Gmail inbox.