I am not convinced that the value add to the undergrad environment will make up for it.
In my experience, graduate students aren't really that effective at research until several years in to their education. From a productivity standpoint, it is largely a loss. Many would prefer to hire post-docs instead. They end up being not much more expensive after everything else is taken into account, and they are ready to do good work from the get-go (which, for people who's livelihoods depend on getting tenure and/or grant money, is pretty dang important).
https://www.science.org/content/article/postdoc-union-reache...
Cooks and waiters in restaurants don't work for free either. Programmers don't work for free and negotiate salary raises.
Every university has numbers on their site claiming how awesome they are, it's meaningless
The point is that by any reasonable standard, HMC delivers very high quality undergraduate education without having a bunch of graduate students doing research and assisting with teaching. Therefore the point made by @CaveTech above is invalid.
https://www.hmc.edu/research/student-research-opportunities/