Since mating individuals is never truely random why does it make sense to use the Hardy-Weinberg model, which?

That's the thing about pre-university level education and the entire model/theory thing - it's all assumed that the world operates ideally. But like my A levels teacher loved to say, "the world is never ideal". However, it is mind-blowingly difficult, and probably impossible, to come up with a model that takes into account of every possible factor. So, it's much easier and more convenient to use a model that has generally false assumptions, but has been shown to be quite accurate. rather than trying, but never being able, to come up with the perfect model.

HW is designed for exactly that.  To show what the population SHOULD look like if mating was random and there was no selection.  If the actual numbers are skewed away from one or more of the expected numbers (p^2 2pq or q^2) then you have a clue as to how the genes are interacting in nature.

It's like doing a study on education.  Given the state of teaching materials (and teachers are included heartlessly in this category) and the general intelligence of the student population, you should be able to guess how the students will perform academically.  The actual numbers are almost certainly going to be off, because it doesn't take into account life outside of school.  The *ways* in which the numbers are skewed can tell you a lot about what is actually happening with the students'  lives in general.

You can use it to identify disequilibrium, which suggests an evolutionary force such as natural selection, gene flow, or genetic drift is at work.

To me Hardy-Weinberg just supports Evolution.  The conditions of Hardy-Weinberg would never be met in the "real-world", there fore evolution is unavoidable.  Organisms have and will continue to evolve.