Pressures to keep certain majors easy
I find the thesis of this book (at least as summarized in the posts below) both disturbing and interesting. By way of disclaimer, I haven't read the book itself.
I'm usually one of the first to be somewhat skeptical about claims about a system's being rigged to help the wealthy and hold back everyone else. That's not to say such issues don't exist, just that it's too easy of an excuse and gets used too much as a consequence. I also like to think that my readiness stems from spending a good part of my life in Berkeley where the general drift is to make everything out to be a tactic of oppression and that I would moderate to the other side of things if I grew up somewhere else. Still, I find the idea that "easy" majors work out well for privileged students but not others because of their connections to certain industries to hold some water. Besides the connections, you're also more likely to do well off of an "easy" major if you have plenty of time to search for a job after school, which often means not having student debt and being able to move back home.
At Harvard, I was always very perplexed by how easy it was to get a degree in economics.* Economics should be a "hard" major because it's a very, very complex topic. It also involves a lot of advanced math. I don't know if the real reason that it is watered down so much is that quite a few well-off students have families with connections in finance, they want to party through school and therefore there's pressure for the university to offer students a path that will accommodate both. That reason sounds at least plausible though, and that's better than most explanations I've heard suggested.
It seems like this effect cuts both ways too. In majors that appeal to students partially through the allure of good job prospects (e.g. computer science), the number of hours expected is very steep. Some of my friends majoring in CS who were also trying to invest heavily in sports had to struggle to keep up their performance on each. I'd argue that the rigors of the major are imposed somewhat artificially in order to define the major against others that let students slide through to protect the ability of students to get good jobs. What if someone is naturally not particularly gifted or, like my friends, wants to do other things, but is genuinely interested in the subject? It seems like we need a stronger signal for how hard someone has had to work for their degree that is external to which degree they got. Possibly this is another argument for beating back grade inflation.
* Friends from Harvard with a degree in economics--most of you didn't take the easy path. Please don't think I'm belittling your degree. There are some very difficult courses that can be taken. However, I'd still argue that you can get through with a pretty small amount of effort.