A major issue is that the amount of propositions and definitions is immensely huge. If you want the type of philosophy you're asking for, it's just analytical philosophy. But that loses a ton of its value. Marx was writing at a time when most people who would read his works had some familiarity with the argument style of the German idealists and were familiar with Kant and Hegel. The definitions, propositions, and argument structures that are missing are culturally defined and flexible, purposefully.
And I believe this is a strength. Playing with language as it exists is useful to convey an idea. Using "is" to mean equal in content or form next to each other is a great use of language for philosophy though it's inherently "contradictory." But isnt that precisely the point of his dialectic?
Making something too abstract (and here I mean, further from the way that one's rationality works on a daily basis) takes one further from what can be understood and be useful. Analytic philosophy (the pure analytic stuff, don't catch me with that claim that Marx was half-half) is mostly shit for this reason. Maybe it's possible to be as analytically rigorous and still make useful philosophy, but I'm yet unconvinced.
None of this is saying it's easy to understand or something, but the difficulty and working through the flexibility to find a complete concept is part of the philosophy itself
, but that is not what the average person experienced/noticed. I heard that shit so many times from colleagues with never even a concept that he was terrible personally or politically.
I'm not going to reply to most of this, it's too long for that and I think I can get my point across is minimal points.
I think your cosine example is precisely what I needed to know I am right (I apologize back for snarkiness, I'm not angry at you either but I do think you're representing a position we must work through as a movement).
The first time you learned what a cosine was, how did your teacher explain it? Was it a mathematical proof listing the assumptions of number theory, 2-D planes, and simultaneously capturing it's geometric, graphical, and algebraic representations in one big swoop? I can guarantee you it wasn't. You learn cosine first in one of the ways (usually simple geometry as the relative lengths, and the teacher shows a triangle and doesn't explain its limitations to 2D because you're still learning), then says "and here's how this looks algebraically, and lastly "now let's plot the values of it" sometime later and you learn about trigonometry as graphical representation. And it's utility in calculus comes years later.
What was the point of this exercise? Why didn't your math book just make a 1 A-4 length list of assumptions, graphs, and images to get you up to speed in 10 minutes?
If you want to create that for a philosopher, do it! It's a great exercise in your knowledge. But that's not what the philosophers are doing, they're being the teachers. (Please understand I'm speaking well of philosophers in general, though I mean good ones specifically.)
If Marx just threw out at once every contradictory way that commodities exist and his "synthesis" of what that means they are in 1 definition, nobody would have a goddamn clue what was happening. His writing tries to get you to follow the thought process, through the contradictory stuff, to the kernel of truth represented by each of them are to greater concept. For your development as a person and thinker, it's much more useful than throwing out only "empirically proven" lists of claims.
I unfortunately think that the position you're staking is strongly correlated to the Western anti-intellectial and pro-STEM-lord bent that is preventing development in a lot of areas. If you have to go and argue with others about what is meant, that is better than just being able to accept/dismiss everything on an "empirical" whim. In fact, it's also the point. Argue that it's empirically false, even, and see how the pushback you'll receive isn't at the level of empirics but at the level of philosophy of science. Then empirics has nothing to say til we decide what proof looks like. Philosophers can pre-empt this by staking their claims in that realm, where rationality is our only tool. The Real is Rational and the Rational is Real, as Hegel liked to say.
And a small point: if you think philosophy isn't needed to be a good Marxist, you're in disagreement with every famous good Marxist I know of. Lenin fuckin loved Hegel and hated his idealism simultaneously.