Personally, I have no problem with professors getting paid less. My only objection is that these savings don’t appear to be passed on to students. When we get much more efficient at manufacturing computer hardware, one of the benefits is that anyone can buy a capable device for $300 or less. But when we get more efficient at generating phds, and therefore have a much greater supply of teachers, the savings are not apparent in tuition prices.
Higher tuition wouldn’t really be a problem if it weren’t for the fact that many people who take on these massive debts are later unable to secure high paying jobs that let them pay it off in a timely fashion, turning them into debt slaves for the better part of their life (or maybe all of it). That’s the risk you take though.
Regarding tuition costs, there are a lot of reasons why it has grown so quickly. One is the growth in administration. When my old university announced they wouldn't be doing any more one year contracts and would instead be going with exclusively part-time faculty, I suggested they look into part-time administrators but they didn't seem to think that was a good idea...
Another is the escalating "arms race" of campus amenities. Four year universities feel like they need to add more and more and fancier and fancier amenities to attract students because they feel like if they don't have a new multi-million dollar rec center and the nearby college does that students will be more likely to go to the other college.
A third reason is that the funds colleges get from states is a smaller percentage of their budget now than it was in the past. One of my friends is an advisor at a Big Ten college and she recently posted on facebook that she was going through some old paperwork that had been left in her office and found the university's budget for 1997. Comparing it to 2019, the university's budget had doubled but the amount of money that it received from the state had only increased by about 25%. That money has to come from somewhere (which is one reason why that university has made a big push to attract international students in recent years since they pay a lot more in tuition than in-state students)