I notice that, unlike on the many other sites where I have participated, it is quite unusual to accept answers on Mathematica Stack Exchange, even ones that clearly answer the question completely. Am I the first to make this remark? (and while I noticed this first with my own answers, investigation shows that I am far from alone).
From a quick look at the stats, math, mo and mma all are in the 63-68% accept rate (with mma being the highest). This doesn't account for the age of the sites (mo being oldest) or the size of the sites (math being the largest), and closed + downvoted questions are excluded (which probably helps math & mo's score).
Every year during the start of a new semester/quarter (esp. during the start of school year in Aug/Sep), the quality goes down due to an influx of drive-by users. These folks are not invested in the site enough to care about accepting answers or upvoting them.
I think it's just unfortunate that your recent spurt in activity coincided with this influx of callous users. However, these are the pains of growing as a community and old timers on this site will be quick to tell you about how good it used to be when it was just us in the ivory tower... I hope you don't pay much attention to these numbers (I know it's hard not to!) and enjoy the site and the community in other ways :)