The way professors get tenure at LACs is different, than say any large research oriented school. LAC professors must be good teachers, first and foremost and must love teaching or they will get very bored at an LAC. It becomes a routine job, for some and a bit of a bubble for some. I think interacting with graduate students was the most helpful part of my undergraduate education! (STEM) Grad students taught me how to thin a sample for an electron microscope, and how to use a lathe. They also told me their fears about the PhD program. Professors never go over that part ! Graduate students often mentor undergrads much better than professors, because they are closer in age, and understand the decision process well, to go to grad school or professional school.
So in my opinion, some of the best interactions I had is missing at LACs, and I did go to a smaller school and have dinner with professors about three for four times over the four undergraduate years. It was a pretty close relationship and eventually resulted in me coming back after two years away, for a PhD. One of my professors even flew me
to a solar energy research lab to encourage me to get a PhD. So I felt I had no lack of close professor interaction.
Also I was somewhat undecided about a STEM major, and the larger university, I could actually walk into a plasma physics tokamak lab, and a wind tunnel, and a microscopy lab and see that stuff first hand!
At an LAC, there is often one spectroscopy machine in chemistry, and an ancient telescope on campus.
I felt like I was going back to the 1920s for science when I visited Swarthmore College, for instance, with my son.
And i know Swarthmore IS a fantastic school with a masters like research program in every major. that about 1/3 of the students take advantage of, It just seems very limiting in the sciences.