How often is it that you have a brand new system, in which you get to choose your language? Unless you are independently wealthy, or part of a funded started (indirectly independently wealthy, partially) the answer is probably not very often. Whenever someone has a brand new, completely open, technological problem, they have a green field.
This is not very common, at least for me. I have a BS + MS in computer science, worked for three years as an employee in two companies, and now own my own small software company (with two guys I pay to write code for me) and have been in business for myself for four years. I charge enough money to pay my people, and my bills, through revenue. That means, by definition, that my customers have to be able to pay. I live in a poor state, without a tidal wave of venture capital. Almost everyone here has a legacy system, which is generating them money, which they can use to pay us. Those systems come with constraints.
There have been three times in my 10+ years of experience creating software during which I was able to 100% choose everything technology related for a project. Once was part of a barely funded start up. The other was part of a successful business that contracted with my company to greatly expand their eCommerce, completely scrapping their existing system and letting me choose everything. The third is ongoing - a customer described their problem in a high level, and nothing existed to solve it. For the third example, I am bound by (light) constraints regarding the other system we are interfacing with, and it has to be web-based. Otherwise, my more than full time experience, has been as a maintenance programmer, or as a manager over a team of maintenance programmers. This guy is way more eloquent than I am about the subject, and way smarter + more successful. Think about what the very successful people have to say about these kind of things.
I think different people, in different states, have different approaches. The most poorly organized organizations, and ventures, had very few constraints. They didn't have to answer to anyone about their technological choices, and typically had money to "build something." Sometimes that results in beautiful leaps forward, for humanity as a whole. I think most of the time it doesn't. Maintenance programming means you are maintaining something useful, for someone that is interested in paying you. You'll also learn new skills, and new languages / technologies / tools, just out of necessity, rather than being freely chosen, with no constraints.