"...the thought of Ember making all these decisions for us — enforcing a convention over configuration — was very alluring"
Alluring, yes. Good? You shall see. When you embark on using an opinionated framework development can, at first, seem easy. It's when those opinions change that you can easily get hurt, however.
I find that convention over configuration often is trying to solve the wrong thing. It puts a tremendous burden on the user to know all of these conventions when being simple and direct usually works just fine.
One example is an Ember RFC I read recently about the required folder structure of Ember projects. It wasn't clear to me at all why they were even doing this. Like, what were the gains? It turns out the entire point is some magic auto-discovery of things like Handlebars helpers.
Alluring, yes. Good? You shall see. When you embark on using an opinionated framework development can, at first, seem easy. It's when those opinions change that you can easily get hurt, however.