I started reading Cold Days, a novel by Jim Butcher, last night. It's number 14 in his Harry Dresden series. I kind of like the character of Harry Dresden; I've read several other books in the series and I enjoyed The Dresden Files during its brief one-season run on Syfy a few years ago.
Unfortunately, I'm not overly impressed with the direction the series has taken. Butcher has fallen into the same rabbit hole that's sucked in a number of other authors in genre fiction. Laurell K. Hamilton, Charlaine Harris, and Janet Evanovich are the three I'm most familiar with, but I'm sure there are others. I think of it as self one-upmanship, an irrational impulse to top whatever was in the last book in a series with something that's even more shocking, unusual, terrifying, funny, or sexual. Butcher keeps introducing new totally evil and ever more powerful supernatural beings that are out to get Dresden; Hamilton has turned Anita Blake's love life into something close to an Olympic sport complete with team uniforms*; Evanovich keeps pushing the envelope on the eccentricities of her characters in an attempt to milk more cheap laughs out of her readers.
Whatever causes it -- an unwillingness to invest time or energy in doing more character development or playing too many video games where you advance from level to level -- it strikes me as evidence of a lack of some basic writing skills. An author shouldn't have to resort to cheap tricks to hold the reader's interest. Just because they're called "novels" doesn't mean an author has to try hit new levels of novelty in every work. It is possible to write novels with recurring characters who deal with variations on the same theme over and over and at the same time have the books become better and better. Most mysteries, after all, are variations on the same theme: something gets stolen or someone gets killed, and the lead character gets to figure out who did it. The mystery is what sucks you in, the various plot twists, and not one upmanship, e.g., in the last book the hero got clubbed with a baseball bat so in the next one the author's going to up the ante by having him shot.
Of course, if you're weak at coming up with a decent plot line and your characters are all rather flat, then what's left? You fall back on novelty and the equivalent of special effects, just like in a bad movie, and hope that your readers stick with you.
The readers won't, of course, but it usually takes quite a few pallet loads of remaindered books for the authors to figure that out.
[*Is Anita Blake's vagina Teflon-lined? After reading some of the sex scenes, you have to wonder how the woman can still walk, let alone go out and slay vampires.]