I will try to answer this by speaking to some trends in the university setting in no particular order.
1) Loss of state funding means universities and colleges are responsible to find the vast majority of their money. Some of this is from students, some of this is through research grants.
2) Universities have moved more towards a business model approach rather than one more education centered. Why? See item 1.
3) Students, i.e. consumers, are demanding more experience with their education. This means universities and colleges are spending a ton of money on extras like fancy dorm rooms, workout facilities, and other facilities and programs that add to the experience of the student but not to their education. This stuff is expensive.
4) Beyond student tuition and fees another revenue source is from research grants. Professors are now being hired and fired based on how much money their research can and does bring into the university. For example, I have seen a range from 15% to 50% of research grant money going to the university, not towards the actual research. What this means is an excellent teacher is worth less to a university or college than a mediocre one who gets large research grants.
5) The increased demand on the professors to produce, research articles and grant money, limits the time the professors are able to spend on teaching. The professors I have seen who are able to be very productive as far of research and teaching at top universities often do not have families. I can speak of my experience at a couple top departments in my field where the idea of having kids, or the professors who did have kids, where treated with some blatant contempt - because kids took away from time they SHOULD be spending doing research.
There has been some efforts by different universities to try and quantify the importance of teaching, often looking at number of students taught by a professor per semester. While I agree teaching should be more greatly emphasized at universities, this matrix is not without flaws. Upper level courses have fewer students, for one.
5a) As a result, the use of adjunct facility and grad students are teaching more and more courses. This is not without issue. For students, they are encouraged to prioritize their own research over teaching. while this makes sense for the students success it further encourages and minimization of teaching and prioritization of research for new faculty.
Adjunct faculty are paid (quite poorly) by the class and often very undeserved in preparation time and materials. Most adjuncts either have to teach a very high course load (I have seen some teaching 6 courses and several different universities/colleges - more than two a place will generally not be allowed because then the faculty would be full-time and deserve benefits) just to make less than most school teachers. For the majority it seems, a full-time job + teaching is what pays the bills. You can probably gather that while there may be a real desire to teach the time to do all that is necessary to make a great class is often thin.
6) There has developed a culture across universities and colleges in the US of a passive student, one that sits and expects to be told without real active participation in the class. Some blame this on standardized testing - teach to the test rather that teach kids to learn, a real struggle in the primary grades since so much, and it appears more, are tied to what the kids do one day of the year. It is very hard work to get students to participate. I think beyond the academic culture students learn in primary school is the idea that college is an experience rather than an education.
7) A push by business that students learn particular skills (i.e. training) rather than get a broad education. This is tough. If the schools move toward the training model, students may learn the skills for a particular job but are out of luck if that job, or range of jobs, are not available. A broad education is supposed to prepare the students to be able to succeeded at just about any job because of; knowledge over a range of fields, development of communication skills, but perhaps the most important but generally over looked, the ability to learn, think critically and creatively, and find solutions independently and in groups to different sorts of problems.
That is about a brief an answer I can give.