It's more that a language and its relative expressive power is not nearly as important to project success as the ecosystem around it. Who can I hire? If I lose them who can I replace them with? What frameworks can we use? How can I get support?

this is tangential to your point, but I feel as though I personally use this justification often in technical projects, a wide base of users often means a large base of accessible supporting material and community. while I'm sure of the utilitarian justification I can't help but feel it's also laziness on my part.