This point may in fact not be entirely original, but it's worth bringing back up: this is a holiday designed to provide the already-fortunate with happiness at the expense of those not so lucky. Why does society stand for this?
There are a couple reasons I guess. One is that Valentine's Day is the solution to some sort of coordination game that couples play - no planning is necessary, it's a holiday, etc.
But frankly, if I were a girl, and my boyfriend only did something special (and "special" in this case is almost ludicrous since everyone else in the world is doing it at the same time) on corporate love day (it hurts me to use "corporate" as a derogatory term, but I have no choice), I'd be pissed off. I'd want that roses->pheasant under duck->souffle->sex to be either a surprise, or on some day that has relationship-specific value. Would I really be so unimportant that only when advertisers bombard him with reminders that every kiss begins with Kay (possibly the best advertising line ever, and one that fills me with rage every time I see it) would he remember to make an attempt to please me?
But my standards are, or would be, high.
Also the whole thing smacks of collusion. By making everyone want dinner reservations on the same (often non-weekend) night, suppliers of romance restrict supply and juice up price like a Jason Giambi bicep. And we, the working stiffs, suffer.