It's definitely an important factor, at least indicts lots of other factors. - is the language suitable for the domain? - is library/community support mature?

It's definitely an important factor, at least indicts lots of other factors. - is the language suitable for the domain? - is library/community support mature? - are there enough developers? - who in the company will support it? It's obvious from HN topics that we are obsessed in language topics. - it also reflect some part of design philosophy, and it could be good or bad for your project depend on the case.