Education costs money. Ignorance costs more.
I don't know for sure. One possibility is the growth of google books - maybe more people are going there to get anything they can for whatever research they are doing. The other thought is that serious research who do need scholarly information may have realized GS is a crapshoot. With no disclosure about the journals they cover, you have as much chance of missing important (and current) research as you do in finding it. Who wants to take a chance of missing something really important. I hope, but don't think, that GS users woke up and realized that academic library databases are far superior for scholarly research - and if it's your library - no one is trying to get you to buy articles for ridiculous prices.
It's not been my experience recently that academic library databases are far superior for scholarly research. In my field (biomedical), they are superior in some ways, but GS wins in others. I find it odd that with all the rest of Google's business growing so rapidly, GS is down so sharply. Certainly Google have not been promoting it much lately, but I wonder if the comScore data is accurate?