I think this is missing the forest for the trees. These aren't the reason schools cost so much and in turn why student debt is so high. Meeting with other scholars internationally has been happening for over a hundred years. European schools often travel to America a lot because conferences are often here, and their costs aren't what American universities are. Despite having similar levels of research output. The high cost is for other reasons. This also isn't why professors ignore their teaching requirements (find time to do both research, which is the higher priority, and teach. You sure can't in 40hrs)
As to the rest of the comment, I am in a lot more agreement with. I don't even think grad student pay needs to even be that high, it would just be nice enough if I didn't need to rely on internships for my cost of living. If I had enough money to pay off my undergrad loans instead of letting them rack up tens of thousands of dollars more.
But one thing I would highly argue, is that research is investing in your own country. Academia is a common place for innovation to be derived from. It is no surprise given you put a bunch of smart people together that are passionate about learning that they make new things. Especially considering how research is literal innovation. I think there's a large argument to be made about how this is a national security issue, and can be justification for diverting military budget for non-weapons based research. War is about economics after all. Really it is about a lot of things besides the actual fighting parts. Innovation has been a key element in America's (and many others) success. It is weird to think that we wouldn't place this as one of our highest strategic assets.