I've taught at 3 Universities as, two of those were as adjunct faculty. I've worked in an industrial research lab. I've worked as a University employee on research grant projects.

You seem to dismiss "the freedom to do research" as an important goal, needing much less priority than teaching.

Let me share some pseronal observations about both teaching and research.

Adjunct teaching is free labor these days. I love to teach but my adjunct gigs barely covered the cost of travel and food. Given the number of hours spent preparing courses, running labs, office hours, and actual teaching, the paycheck was WAY below minimum wage. I can't afford to teach.

There are some facts about research you need to consider. First, research takes time. Second, it takes money. Third, it takes focus. Fourth, research usually doesn't succeed. Fifth, we really NEED researchers. Lets look at them one at a time.

Research takes time. A research project can take 10 years to produce something that can be useful. Do you like the wonderful new AI Neural Network projects? Are you amazed at the Alpha-Go program that beat the world Go champ? I worked on that exact problem...in the early 1990s...using Neural Nets. After a couple years I gave up. The current leaders (overnight successes) didn't give up and didn't succeed until around 2010. That's the advantage of being a tenured professor.

Research takes money. There used to be government research labs (until Reagan killed them). Big companies ran big labs. Xerox had PARC (which gave us windowing, mice, and the ethernet), Bell Labs gave us microwaves (the device), and check readers (early Neural Nets), IBM gave us disk drives and scanning microscopes. Universities gave us AI and robots. ARPA (the government) gave us funding for a thousand new things.

Now? Not so much. Government labs are gone. Xerox PARC and Bell Labs are gone. IBM management is doing everything they can to starve IBM Research. Microsoft killed a research division. Google (Alphabet) is killing research efforts. ARPA became DARPA so all your research had to be for "defense".

All of the tenured professors I know spend a LOT of their time begging for money. A tenured professor's "research" these days amounts to hunting for money to pay for students to do the actual research. The military is the primary source of funding these days... and you wonder why "killer robots" are coming?

Research takes focus. IBM Research (Ralph Gomory) pointed out that a research project takes an average of 10 years to produce a result; e.g. Axiom, a computer algebra system developed at IBM Research, took over 10 years. It involved dozens of researchers and millions of dollars as well as dedicate management and lab space. It was a career project for the project lead (Richard Jenks). The Neural Network story is the same, except it happened in Canada. Tenure gives you the chance to create an area of science (e.g. Gilbert Baumslag in Infinite Group Theory).

Research rarely "succeeds". Gomory (IBM Research Pres.) pointed out that less than 10% of all research projects produce a useful result, e.g. my work on re-writable paper, similar to the Kindle paperwhite, my work on automated robot assembly from CAD drawings, etc. Unfortunately you can't predict which research projects WILL succeed. Certainly nobody would have predicted that Neural Nets would beat a Go champ (and thus, my NN-Go work would be vindicated?).

Fifth, we really NEED researchers. When my parents were born plastic did not exist. Everything was wood and stone. Look around you and count the number of plastic things you can touch. When I was born transistors didn't exist. You probably can't count the number of transistors you use in a day. When you were born self-driving cars didn't exist. In 20 years you won't know a single person who knows how to drive.

So now you propose that professors no longer get tenure. You want them to justify their job every year (they do already in the form of grant applications). Next you will propose that professors get rated on a scale of 1-5 and that the '5' performers should be fired. IBM Research did that and it killed the whole division. Edward Demming (helped restore Japan to a world economic power) debunked the whole rating idea but management won't listen.

Tenured professors are the "last man standing" in the research arena. Beware what you kill; there will be nothing left.

I have a counter-proposal... Professors should get tenure AND GUARANTEED 100k per year minimum funding for the life of the tenure. Sure, some will "retire on the job" but some will create Deep Neural Networks. Place your bets.