For me it's not even about "time to learn", but the fact that I never can be sure I know how something like this works. Even that little detail about how `resources` automatically defines so many routes… yeah, it's kinda convenient, but I would be more comfortable if I'd have all of my routes explicitly defined somewhere, at least in a framework with scaffolding. When an app written like that grows, and I'm not the only developer, and that guy before me was clearly using drugs — well, that really becomes scary much quicker than in a simple Flask-style framework.
Curiosity: is that a concern only with routes? Or would you also like to have a explicit control of which middleware you are using too?
Because if the latter, it feels like a web framework isn't for you. But you should definitely consider Plug (http://github.com/elixir-lang/plug), which has all the pieces and you just need to put them together (a simple router, a bunch of "middleware", etc).
