Rothfuss is a special case as he, or at least his publisher claimed that the next two books were already written and only needed to be edited. That was one of the reasons I bought the first book early before any later books were released. Starting an unfinished series is always a gamble, I generally don't mind it but I'm also okay with not always getting a satisfying conclusion, or any conclusion at all. But I don't appreciate being lied to about the state of the later books like this.
For larger series with more than 2-3 planned books I would generally be wary now, and the only one of that kind I'm reading is Stormlight Archives by Brandon Sanderson who has a very solid track record of delivering on his promises.
This doesn't justify the vitriol these two authors receive at times. But it is certainly valid to be disappointed in them. It has also lowered by opinion about their writing, as in both cases it has made it clear that they wrote themselves into a corner, and that some of the most intriguing parts of the early books probably have no substance at all and were mere illusions.
For larger series with more than 2-3 planned books I would generally be wary now, and the only one of that kind I'm reading is Stormlight Archives by Brandon Sanderson who has a very solid track record of delivering on his promises.
This doesn't justify the vitriol these two authors receive at times. But it is certainly valid to be disappointed in them. It has also lowered by opinion about their writing, as in both cases it has made it clear that they wrote themselves into a corner, and that some of the most intriguing parts of the early books probably have no substance at all and were mere illusions.