They're missing something, those like Robert Reich who would argue that we should worry less about four-year college and rally behind trade and technical schools as a low-cost alternative. Many of us who've been in the position of interviewer or boss are looking for someone with the critical thinking, creativity, and understanding fostered by general education in the humanities and basic sciences. It may be possible for a great candidate from a tech school to have that critical thinking on their own without that general education, but it's less likely.
Further, there's value beyond the directly vocational in the general education that comes with a bachelor's degree. More knowledge in the humanities and basic science makes for better citizens, a more informed electorate, and an all around improved society. While some very few attain such knowledge through self-study, on the whole we're more likely to get that from widespread college education. It truly is a public good and good for the general public.
Full college may not be for everyone. Trade and technical schools serve well to train workers who are not prepared for college. But if we confuse their playing a useful part with somehow replacing the benefits of expanded college graduation, we risk the reduction of potential for whole generations.