[lobrien]

Since you're "coming from the Python world" you have a good case-study in how a bunch of things outside of language design are crucial. Python has essentially won the race to be the next major language among scientists and that's tied up with a virtuous circle of libraries for, e.g., numerics, statistics, data viz, machine learning, and even within many scientific disciplines (e.g., astronomy). The virtuous circle also includes learning resources (books, Websites, conferences) and the ability to have someone check / talk over your code.

For what it's worth, F# is trying to get that same virtuous circle rolling, but there are a few areas (cross-platform dataviz, interactive notebooks) where F# just doesn't have quite as good a story as Python.