Why vim and not emacs? Why OS X and not Debian? We all have the tools that we end up using, when we end up using them. When I first came across Bootstrap it was at a time when there was plenty of people using LESS as well as SASS, it's only as time has gone on that people have started using SASS more, but there's still plenty of people I know that use LESS as well.

There's plenty of SASS based forks now though, so the community uses the tools as it can.