@MWolf: And you present the argument for LACs well except that it is not universally true that undergrad research assistants simply do manual chores. (Although may be accurate for freshmen undergrads.)
Your post does raise an issue about quality of research at LACs if LACs produce research based in significant part on the work of undergraduates without the assistance of PhD degree seeking grad students.
The overwhelming amount of research dollars invested by private companies & the federal government go to research universities–not to LACs.
As for letters of recommendation from faculty members for undergraduate students, I know many undergraduates through many decades who have received detailed letters of recommendation from professors at research universities among the 30 universities listed in my post #29 above.
I agree with @theloniusmonk that the differences are greatly exaggerated.
Also important to note that the ardent LAC supporters argue that LACs are superior because professors focus on teaching, and not on research; then when the issue focuses on research, LACs are magically superior to National Universities because students work closely with professors on their reseach at LACs.
Research universities have the funding from the federal government & from private industry enabling these National Universities to purchase the best equipment & to fund PhD programs.
Would one rather be the sole aid to a city councilperson or work as a legislative aid to a US Senator ? (Big fish in a very small pond versus small fish in a very big lake.)