I don't disagree that there are other criteria besides performance, only that Go services will likely cost an order of magnitude less than Python services, and the development velocity is pretty much on par (and much better for concurrent tasks, since Go is much more expressive here).
Go is heavily optimized toward performance and rapid development. Go also takes a hard philosophical bent against redundant features, like exceptions, under the "less is more" and "simple is better than complex" axioms; it's actually the same philosophy that Python's zen espouses, except Go actually adheres to it.
Regarding libraries, there are numerous web frameworks and several ORMs. I'm unfamiliar with Django, but I will say that Go's standard HTTP library is a tremendous improvement over Flask. Also, I've not yet found an ORM that saves time or trouble over hand-coding SQL (in particular, SQLAlchemy is a real bear).