What is it about the series

OK, I’m doing my first rant today. What is it about series that makes them so popular? I just don’t get it. Julia Quinn is a perfect example. Readers just can’t seem to get enough of the Bridgerton family. I’m pretty sure I’m in the minority but I just completely lost interest in this family after the third book. And I can’t for the life of me figure out why so many people are so hot to read a story about the mother. She’s just not that interesting a character to me. She strikes me as being a twit.
Mary Balogh is another author who fell into this that I don’t read any more. Her earlier stories were very good but I read two of the Slightly books and lost interest. I can’t see me ever reading her again which is a shame.
Sherrilyn Kenyon’s Dark Hunter books are another series I’ve given up on. They started out interesting but now it’s way too much of the same old same old. I bought her latest release but just haven’t been able to read it. I know I’m in the minority but at this time I could care less who Ash ends up with. I don’t mind if an author writes two or three books in a series but after that enough is enough.
For this type of series, there seems to be such a build up to the final book that it always ends in disappointment. Whether it be Ash, Rothgar or Wulfric.
For the most part each succeeding book seems weaker and weaker, rather like clones being weaker than the original.
The only exception to my dislike of series books I’ve come across is the Compass Club series by Jo Goodman. I think in part because she has put such a unique spin on her books. I enjoyed each and every one of them.
And Connie Brockway, in my opinion is wise. Her Rose books are only a trilogy. That I can handle.
I may be way off base but I think one of the reasons is because it’s easier on the authors. They already have half the cast of characters set in place. By writing a series, they don’t have to establish histories for the main characters. I don’t like this. This may be sacrilege but it smacks of laziness to me when they write five, six or seven books all based on related characters. Move on already. Be fresh. Write something new.
Another thing that irritates me is when an author starts a series she’s almost guaranteeing herself a fan base that will buy all books in the series just to see how they end. I prefer to purchase each book on an individual basis, not because I’m being manipulated into buying book four of eight.
Another thing bout series books that drives me batty is the frequent requests I read on board for the stories of the most insignificant of secondary characters
“Author A, have you ever considered writing a story about the niece of the sister-in-law of the aunt of the nephew of the hero? She made such an impression on me in that one paragraph you wrote about her that I would love to read her story”
WHY????
I just don’t get the appeal of the series.