ALONSY: V podstatě Gaimana cituješ (ale to ty asi víš) :))
You're complaining about George doing other things than writing the books you want to read as if your buying the first book in the series was a contract with him: that you would pay over your ten dollars, and George for his part would spend every waking hour until the series was done, writing the rest of the books for you.
No such contract existed. You were paying your ten dollars for the book you were reading, and I assume that you enjoyed it because you want to know what happens next.
It seems to me that the biggest problem with series books is that either readers complain that the books used to be good but that somewhere in the effort to get out a book every year the quality has fallen off, or they complain that the books, although maintaining quality, aren't coming out on time.
Both of these things make me glad that I am not currently writing a series, and make me even gladder that the decade that I did write series things, in Sandman, I was young, driven, a borderline workaholic, and very fortunate. (and even then, towards the end, I was taking five weeks to write a monthly comic, with all the knock-on problems in deadlines that you would expect from that).
For me, I would rather read a good book, from a contented author. I don't really care what it takes to produce that.