If you only pick tools that everyone else knows so your hiring pool is large, then new tools never stand a chance of being used. You would stagnate all progress in the industry!
It's funny because when Paul Graham writes articles about how the web lets us use whatever language we want (see http://www.paulgraham.com/avg.html), everyone celebrates the possibilities of writing their web site in their favorite lisp dialect. Yet here we have this evil engineer who picks a technology he likes, successfully improves a product and meets business requirements with it, and is ridiculed for picking a relatively obscure technology!
Check out tiobe. I wouldn't be surprised if in a year Scala passes the combination of all lisp/scheme dialects in the rankings.