Also I should point out that the variable names they use in these formulas are the worst possible, single letters, X, Y, some random greek numeral. If a programmer wrote variable names like that they would be fired.
With respect to the use of Greek letters and such, I do lament that many writers of mathematics fail to define their terms. Instead assuming that the reader is fully conversant in the domain, when often a single paragraph at the start would add a great deal to the clarity of their work. However, that doesn't mean that the use of such variables is bad, they just need to be defined.
The benefit of the mathematical notation is that it permits conciseness and lends itself well to symbolic manipulation (that is, a large portion of what we do when we do algebra and calculus). The former is a tricky subject, conciseness at the cost of clarity can be a net negative. But the latter is crucial to a lot of work, the way that we write programs does not lend itself well to symbolic manipulation and would be counterproductive for mathematics.
In fact, I've often had to translate programs into a symbolic notation in order to try and decipher them because the long descriptive names, as useful as they are in isolation, ended up rendering the total procedure nearly impenetrable. Or at least unanalyzable. And the conversion to a symbolic notation permitted me to simplify the program substantially because I was able to apply ideas from algebra to the program (often boolean algebra, in particular, this is a very useful practice for condition heavy code with lots of predicates).
As to your original criticism, I'll wager that more people in this world will understand f(x) = 5x + 3x^2 than will understand rudimentary code, as it is taught a lot more than programming is. I don't mean anything negative when I say this, but the only people I know who complain about math syntax are programmers. By changing these conventions, you are asking all mathematicians, physicists, chemists, most engineers, economists, etc to change. I will wager that over 95% of them will not prefer your style.
Finally, the trouble with replacing f(x) with Y is that the former tells me I'm dealing with a function. The latter does not. In fact, for many mathematicians, y = 5x + 3x^2 is a constraint, not a function.