1. An electoral system which can allow someone who does not have at least the popular vote to 'win' is flawed particularly in a presidential. Presidential elections are usually hard to fuck up. You usually get this issue in pariliamentary systems which uses majoritarian systems.
2. Don;t mean shit. A bad electoral system is a bad electoral systems regardless of political affiliation. Though it is understandable to for Dems to feel that way as the Democrats have won the popular vote in every Presidential election since 92 apart from Bush's reelection.
3. All votes would become equal in importance. If you live in a deep red/blue state and vote the other way, than your votes really counts for shit.
I like how any system you personally disagree with is automatically 'bad' or 'flawed'. It's almost like you have no idea of the point of non-proportional voting systems in the first place.
In Australia, each of our states has an equal number of Senators, which are elected proportionally on a per-state basis (as opposed to proportionally on a national level), so that if the more populous states like Victoria or NSW vote a certain way, their interests won't overrule those who live in WA, Tasmania or Queensland just because there are fewer people in those states.
It sounds like you want a system that allows 51% of the population to rule over the other 49% on every issue, as opposed to different interests and ways of life (which often have a geographical basis) being respected and defended. I don't want farmers and our agricultural sector to be screwed over just because there are more people in Melbourne and Sydney, and those people happen to have no idea how farmers live. Just because farmers are fewer in number than urbanites doesn't mean they should be denied their voice.
This applies to the US Presidential Election as well: US States are culturally, historically and politically distinct, far more so than Australian states, and the states with smaller populations shouldn't be denied their voice either.
I agree that the Electoral College isn't a perfect system (though Electoral College votes are somewhat normalised by population anyway), and I believe that we should cut out the 'middle men' that are the Electors themselves, but the notion of having a system based on voters by state rather than a nationally proportional one is a good thing, in my view.
So to all those people whining about "muh popular vote", remember that Shillary won the popular vote to Obama in the 2008 primary but got fewer delegates.