It would make all states politically irrelevant, which means that a vote in California would be worth the same as a vote in Wyoming. Under the electoral college, a Wyoming vote is worth 3x a California vote.
It also only goes into effect only if it removes other swing states’ influence. It’s not like Michigan is going to give up its status while Ohio, Pennsylvania, and Florida continue to be swing states.
It’s also weird that since 1992, only one Republican presidential candidate has won the national popular vote, and yet 3 have won election (counting W twice). That doesn’t sound like a healthy democracy.