SQ: why transient instead of enhanced keymaps?

[Daniel Colascione]

Transient is now an included battery that provides quick-access menus, mostly famously for magit. People love it. But the overall effect of including it is that we have two keymap systems, one of which, transient, isn't customizable the same way keymaps usually are. Why wasn't transient functionality provided by making keymaps better? I don't see why in principle they couldn't do the same things.