I fully agree, and I'd like to extend it to their families as well. But... you ask "why not" and the simple reason is that only they could enact such a law. And even when the laws are in place -- Trump ran roughshod over the foreign emoluments clause, and there were zero consequences. Why would the richest and most powerful Democrats set such a precedent, only to have it turned around when they're in power and stand to profit?