I don't think this will limit contributions, this is the direction frontend development is going in terms of CSS Preprocessors, currently Grunt makes this workflow easier. I understand the amount of dependencies can become overwhelming, but once you start making use of them in every project, you will realise how much they increase your workflow.
I will try and build out a Vagrant box tonight to make this process less combersome, so that way you will only need to have Vagrant and VirtualBox installed then the rest is all done for you.
Just to note, currently there is nothing stopping anyone using Codekit to compile from SASS to CSS, just try not to check in the CSS and only the SASS file in that instance or make sure your SASS settings are the same as these
https://github.com/modxcms/revolution/blob/develop/_build/templates/default/gruntfile.js#L81 if you want to check in your CSS file.