Where widely understood, I consider a Greek variable to be vastly superior. The problem is how well it's understood. Delta is an example of a succinct variable which has a well defined meaning which to encapsulate in a named variable either requires a long name or leaving out some nuance (delta isn't 'change' which is ambiguous in English, but the difference between two measurable things.)
Keep in mind we use special single letter variables all the time, sometimes multiple for the same concept. Multiply, divide, add, subtract. You learned them all in early education along with everyone else, and now you have a universal set of symbols to express arithmetic concepts.
Would we be better off if every occurrence of '+' was replaced with 'sum'? I don't think so, but that doesn't necessarily mean that loading up with single letter variables that people aren't familiar with is better. It's entirely to do with how familiar the target audience is with them. A library targeted for use by scientists might see benefit to more of them, while one targeted towards being accissible to many people might not.
Single letter variables (including Greek ones) are great when they stand for something, or are well-known so they don't need to stand for anything.
If you stick to convention and use stuff like A for array, i for index, r for root, δ for small change (a delta), ε for error, Σ (Greek S) for sum, Π (Greek P) for product, etc.
It's only when you start using variable names as if they were free variables when they really aren't that you get into trouble with comprehension, especially from people not in your field.
It think this is somewhat similar to: many chinese characters vs ASCII. Neither is the superior notation. I prefer to write words by concatenation of multiple ASCII letters instead of one letter symbols, but that's due to my cultural background.
Keep in mind we use special single letter variables all the time, sometimes multiple for the same concept. Multiply, divide, add, subtract. You learned them all in early education along with everyone else, and now you have a universal set of symbols to express arithmetic concepts.
Would we be better off if every occurrence of '+' was replaced with 'sum'? I don't think so, but that doesn't necessarily mean that loading up with single letter variables that people aren't familiar with is better. It's entirely to do with how familiar the target audience is with them. A library targeted for use by scientists might see benefit to more of them, while one targeted towards being accissible to many people might not.