The "magic" is what makes Rails extremely fast to prototype with. For me, at least, it's what makes working with Rails fun, since it lets you spend time writing application code instead of repetitive business logic.
It's also what leads a less-experienced developer to get in over their head quite quickly. My only problem with programs like Dev Bootcamp is that complete newbies shouldn't be learning Rails, they should first be building an application with a much-less robust framework so that they truly appreciate (and are wary of) how much "magic" is in a framework like Rails.
As a side note, if you haven't done so already, take a look at express for node.js. You say you're "waiting for the successor", and it seems like you want something less all-encompassing than Rails.