I believe the system at play is fine, Hillary's defeat is largely attributable to her unwillingness to visit certain states and bad campaigning. It seems like a terrible statement to respond to that sort of defeat to instead suggest "Well I want to make it so that sort of campaign can easily win next time".
I fundamentally think the system as devised is only deficient in that its a First Past the Post system. I'll agree that I don't think Battle Ground States are a good thing. But if you remake the electors to be proportional such as the Andrew Yang proposal that you know, now since its not FPTP, you have a reason to campaign in say Utah or Alabama as a Democrat, or go to California or New York as a Republican, you make the electoral college a better system. Basically I don't like getting rid of the EC because then presidents focus and gear their campaigns are big media markets, ignore rural areas completely.
Plus I agree with Yang's intuition. Its like, Man, Democrats have lost two elections recently because of this EC, and now Democrats prefer a system that makes those loses not possible; despite those rules being in place for an extremely long time. It does remind me of California Republicans cynically wanting to split the state because they don't want to put in the work of winning in California.