I never really understood the reasoning behind *any* holidays, to be quite honest. Celebrating a specific person, or a specific event... if it's so great to be significant, you should have it celebrated every day of your life, even if in a small way.
Holidays are really just the lazy people's excuse to say they really care about the thing in question. A bad significant other, who hardly spends any time with you and doesn't really care for you, can immediately get an A+ simply by participating at that designated time of year. It's ridiculous and just deludes people and those around them into thinking that they actually care about (insert holiday reason here).