I think you're vastly underestimating the amount of effort that would be involved in comprehensively judging an entire field.[0]
Sure he's a professor, but he only has so much time in the day. At some point he has to say "Right, I think that covers everything important" and get on with teaching.
Not to mention, according to a quote in this thread Spike himself disagrees with you:
>He also asks backers to send in their suggestions for the list "because of course there's going to be stuff I left out."
[0] Although I might just about expect such a thing from Knuth...
That would be comprehensive. As I said in a sister answer, I would expect a little tweaking of the list after criticism and feedback, but I wouldn't expect large changes to it. If Jim Shepard published a list of essential reading for literary fiction writers, I would expect it to be his best idea about what aspiring fiction writers should read to learn from. Writers who could emulate (or whatever writers do) the authors in that list would be well on their way to being good writers.
It doesn't mean he has to have read every lit fic short story or novel out there. It does mean that these works form a comprehensive display of whatever it is that makes good fiction.
Sure he's a professor, but he only has so much time in the day. At some point he has to say "Right, I think that covers everything important" and get on with teaching.
Not to mention, according to a quote in this thread Spike himself disagrees with you:
>He also asks backers to send in their suggestions for the list "because of course there's going to be stuff I left out."
[0] Although I might just about expect such a thing from Knuth...