I've been considering this a lot lately myself, the biggest pro I've come up with is that with the right project a lot of people can easily dive into customizin

I've been considering this a lot lately myself, the biggest pro I've come up with is that with the right project a lot of people can easily dive into customizing / theming the work and if you're careful existing themes might be really easy to integrate. If nobody else is going to be editing the project then it's really just a tradeoff between your own time vs download size, if you can afford to shave a few hundred kilobytes off your first page load that can be a big improvement for many audiences. I've been favoring Skeleton as a significantly lighter alternative, although it is very small in comparison to bootstrap - http://getskeleton.com http://getskeleton.com.