This sounds like constraints for a suit-and-tie company where programmers and teams don't have much autonomy. Maybe this is your definition of a professional company. In other kinds of settings, the stars may align in favour of non-mainstream languages. If your project has to attract good programmers from inside the organisation and a modicum fearless propellerhead attitude is part of the culture, it may be worth it. But of course forcing a team to adopt anything should not enter the picture.
