I agree, it's a very poorly positioned sale in my opinion. Tax refunds are out, since the majority of folks in the US don't file their taxes until right up to the April deadline. People who forgot to buy something during the winter sale
kinda makes sense but it's really really soon. China is a growing market for Steam, but Asia as a whole still ranks #3 according to
their usage stats. If it was encouraging people to buy Valentine's presents, they didn't theme it very well.
My guess is that this is once again Valve experimenting with their formula to see how people react to having a big sale just a month after the last big sale, with the added bonus of it coinciding with a big holiday in an emerging marketplace.
There are a lot of developers/publishers this time around that aren't taking part in the sale, and I suspect it's because they don't want to be part of Valve's experiment. At this point they're probably wondering if a week-long "big" sale every month will become the norm. The data might suggest that sales bring in big numbers, but I imagine publishers are wondering if buyers will be willing to pay full price for games if they're presented with so many sales opportunities throughout the year.