Problems that are clearly formulated are easier to solve than ones that are opaque.

At the very worst, it lets the devs know where the users want new features. At the very best, it helps crystallize aspects of the problem that make a solution easier to find.

User feedback is always a gift. Even if they are yelling at you, they're giving you valuable information.

I suppose there are some developers who are not advanced enough to contribute to the project, but smart enough to use a framework? I don't know: Tom Dale did reply to the gist, and mentions there are non-trivial CS problems being solved.

Ember is actively trying to compete with angular (backed by google) and others - and I think the people rooting for ember are just people feeling let down after deciding to move forward on it in production.

edit: Tom's actual quote: "trying to solve are novel computer science problems"

I wonder if this is one of the named heroes in the letter, wishing to maintain his position in the group, however weak.