Language desirability has a huge impact on developers.
Is it easier to hire with these languages?
I met a guy at Silicon Milkroundabout (a jobs fair for London startups) who was hiring developers for a Haskell-only startup.
Generating interest from developers was not a problem for him, he assured me!
Can coolness be quantified?
'Most loved' and 'most dreaded' are rankings for languages on the Stack Overflow Developer Survey.
See also MeasuringLanguageUsage.