JFP...
... agree with you, and I think there may be a few more resignations to boot.
The only bit I disagree on and agree with Hon on (A first, as I think he is a bitter twisted person who failed J2) is on boredom.
The B757 fleet don't have the diversity, but do have a lot of sitting around in an office all day - not what pilots want to do. It has a big impact.