Only because you're used to it. In fact, standard notation is much harder to read because it's ambiguous, often to the point of actively introducing errors. See:
http://mitpress.mit.edu/sites/default/files/titles/content/s...
> If you want I can give you examples
No, I don't dispute that blackboards are useful. What I dispute is that their utility is so high that we ought to design mathematical notation around their limitations.
>It seems tempting to have a single unambiguous notation for mathematics. But In constructing such a language, one will quickly realize that doing mathematics becomes an intensely arduous task.
When talking about math, our notation doesn't have to be precise, and that's ok.
> No, I don't dispute that blackboards are useful. Just obsolete :P
Re: your last paragraph. I only went to the end because I knew that there must have been a good example in the questions. If you want I can give you examples from the middle of a talk.