I would say we have come a long way.

Mathamaticians absolutly do spend effort on making their work readable. However, this readability is general not within the equations themselves, but rather in the prose around the equations and in how the proof is presented. Of course, skill levels vary in this, and most mathematicians only ever write for other mathematicians, so that is the audience they have practice with (and, if you read a math paper, likely the intended audience).

Also, generally the "equation" is not what mathamaticians are even trying to explain because it is vastly simpler then what they actually worked on, which is the proof.

For example, suppose quadratic equations were actually really difficult, and a mathamtician finally figured out how to solve them. She would probably say something along the lines of:

"A quadratic equation has solutions x=(-b +- sqrt(b^2 - 4ac))/2a.

[Entire paper talking about how to complete the square]"

The entire point of the equation is to be simple to write down and use. It is not intended to be understood.

Sometimes they say an equation without explanation. That is either bad writing, or knowing the audience. Ideally, every equation would come with either an explanation or reference; but if I am writing a research paper, I am probably not going to cite every fact that can be found in an undergrad calculus textbook.

What must be noted though is that historically the language of mathematical formulas, unlike more "human-readable" text, has been designed to serve several distinct purposes, and conveying the meaning was originally not the most important one; rather, the language of formulas serves the purpose similar to that of programming languages of today, which is to let one to efficiently and, to a large extent, mechanically perform - and thus radically simplify - 1) calculations; 2) logical reasoning; 3) transformations that lead to discovery of new facts.