I wouldn't swear to the WHY of it, but there's a general surfeit of wordiness going on all over novel-land (not just in genre-ville). It's an on-going issue that dates back to the days when writers got paid paid the word, even for full-length manuscripts.
I have seen lots of books, on the other hand, that told cracking good tales in 75-90K words. Most Louis L'Amour westerns, the original run of the Destroyer series, and also the Executioner, fit this model. They were formulaic in some cases (especially when Sapir and Murphy weren't speaking to each other), but the prose was taught, to the point, and (most importantly) moved the story along in an entertaining manner.
There's no reason this can't be done here and now, regardless of genre. Just needs a willingness of author and publisher to sacrifice heft for a tight, motorvating story.