I hear more people rag on V-day than any other holiday of the year. Yeah, it's commercialized and corporate societal blahblahblah, but I don't think it is any more than the other holidays.
On Halloween, 'the man' tries to sell you fear and excitement and candy. On Christmas, they try to sell you family and food...and candy. On Easter they try to sell you...mostly just candy. (Seriously, what's the secular rationale for Easter??)
If I had to guess, I'd say the societal requirements for Valentine's Day just rub people the wrong way. The other holidays "require" people, too, but in a much more flexible way. Spend Christmas with a random hobo and no one cares (they may even admire you for it). But to spend Valentine's Day without a date...! Oh, you poor thing! Look how socially inadequate you are! Especially when you're a kid...ah, middle school drama~
And even when you HAVE a date, the pressure is still on. You and your husband aren't doing...ANYTHING special for Valentine's day? Looks like someone's relationship is in trouble~. XD
Of course, being far removed from any sort of romantic concern, I don't see that as too much worse than the pressures you're under to 'perform' on other holidays. But obviously, other people do. I wonder why.