"\frac{4}{5}" is exactly what I wouldn't like to have.
Is exactly what I would like to have, of course.
I really don't see how this is more horrible than "\frac{4}{5}". In fact, it's fewer keystrokes.
"\frac{4}{5}" is exactly what I wouldn't like to have. "4/5" is not - because I do not know what will become of it. Simple example: I do know exactly what will become of "\frac{4}{\frac{10}{2}}", but not what will become of "4/10/2".
It's as simple as this: I want to type what I mean, and I want what I see on the screen to reflect what I mean.
You're contradicting yourself! You type "\frac{4}{5}" and expect NOT to see what you just typed on the screen, right?
Well... did you really understand the line you replied to? Hint: reflect is the word you are looking for...
...when fits of creativity run strong, more than one programmer or writer has been known to abandon the desktop for the more spacious floor. - Fred Brooks, Jr.