"why, say, they apply to Go but not to Python 3.0"

That's sort of a terrible example since python is ill-suited to many (might I dare say a clear majority of?) production environments. The field of general-purpose production languages is actually pretty narrow. I somewhat agree with your point that the reasons were on the superficial side. Nevertheless, people are dissatisfied with the C/C++/JAVA trio and efforts to replace them have so far failed to stick (D comes to mind).