We certainly could. We could also include a whole bunch of other modules as well. It is difficult to gauge how many customers use a particular module to warrant it's inclusion. We came up with the initial list based on our experience with some real customers.
We realize that one size may not fit all - that's the reason for including a README with detailed information on the modules we included and how we built each application in Cool Stack. If a customer needs to rebuild something (to include some other module for instance), he can then use the same compilers/options we used and achieve the same high performance.