No. Try to layout a document on A4 while maintaining at least basic standard rules (e.g. lines of 8-12 words, a pretty text body layout, e.g. a "nice ratio" like 3/4 or 1/2, with standard margins, that is 1 on top, left and right and 2 on bottom). Since your font size will either be 11 or 12 pt on A4 because otherwise you use less than half of the paper or your font is really huge, you're not left with many options.
I wouldn't be so hasty to dismiss hundreds, perhaps thousands of years of aesthetic tweaking by experts as voodoo simply to defend a page size and proportion whose primary advantage is not aesthetic but function.
No units because its all about proportions. E.g. the bottom margin is "double" so it can accommodate page numbers and set the text body on the "horizon".
