As per wikipedia - St. Valentine's Day began as a liturgical celebration of one or more early Christian saints named Valentinus. SO this make the day a more religious day. Surprise!!! isn't it. Especially because display of Love except to God and human as overall is not usually related to religion.
I think that the day was celebrated the way it is now not because of the importance it may actually have. Like as St. Valentines' memory or any other reason followed by various cultures across the world. It has more to do with the fact that there was a opportunity sensed by various industries for this particular day. Industries dealing with clothes, accessories, gifts, flowers, greeting cards, etc.
May be not flowers, those just go along nearly everything but certainly big players got into the play and tries to explore and exploit the opportunity of big Sales which would be possible if the day was celebrated at a huge scale. For that, the audience has to be identified. Adults and married people are little more responsible on their expenses, so the best target was the young. That's what happened!!! The result, I need not mention any more.
|Happy Valentines day|
Yes. The answer lies in two of the human behaviour. First, the instinct of conflict. When elders tell you don't you do it, internally there is an urge to really do it. So, what elders have also been suggesting - don't go fooling (loving) around. And the urge says - If there is a chance, I will.
Celebration of Valentines day did not give the chance but gave a reason not to be alone, at least on this day so that one can hold himself/herself up against peers. Strange but true. No one has to agree but lets not disagree.
And the second of the human condition which led to success for the Industry for this day - Expectation. If there is someone to give you anything like gifts/care/love.. and if there is an occasion to give so.. any human will expect to get something of it. So, people expected love and gifts as there were people to give and occasion too. And it just kept happening years after years after years.
More to come, hopefully. And yes, this is purely my work of fiction and imagination. Celebrate it or not, your choice. Will I? Do I? that's a different theory.