Using full names like that might be fine for explaining a physical rule, or stating the final result of some calculation - but it certainly would be cumbersome and difficult for actually carrying out the calculations. In many cases we already fill pages with algebra showing how things can be related and rearranged to arrive at new results. That kind of work would be intractable with full word names for the variables, partially because you'd be constantly spilling off the end of the page trying to write the steps; but also because having all that stuff would actually obfuscate what you are trying to do - which is algebra. And during that process, the meanings and values of the pronumerals is not as important has how they interact with each other. So the names are just a distraction.

For setting up an equation, and for stating the final result, the meanings of the variables are very important; but during the process of manipulating the equations to get the result you want the meanings of the letters are often ignored. You only need to know that it is something that can be multiplied, or inverted, or subtracted, or whatever. Eg. suppose I want to rearrange to get the velocity. I don't care that I'm dividing both sides by the air density times the drag coefficient and the area... I'm just dividing ρCA, which is an algebraic blob whose interpretation can be saved for some other time.