This way Lisp would never ever require nesting the same kinds of parens again, and it would become more readable. Nobody would any complain about ))) or need parens colouring any longer.
On my quest for parens, I discovered several characters that would be very useful to add to the reader or predefine as standard library. For example, Lisp could support Roman numeral atoms made from ⅠⅡⅢⅣⅤⅥⅦⅧⅨⅩⅪⅫⅬⅭⅮⅯↀↁↂ; ⚐ ⚑ could be used as flag symbols by the user; for very dangerous side-effects one could use ⚠ rather than !; for side-effects affecting variables other than what's passed one could use ‼ and for very desirable side-effects one could use ❣.