Biggest issue with just going popular vote...
new york city
LA
chicago
those 3 CITIES combined, -as of 2013 had 15 million people in it.
take out 25% for under 18's 11.25 million 60% of them vote 6+ million voting... say 70% vote for one candidate
5million votes is higher population than the lowest (population wise) 5 STATES combined.
also there is the urban vs rural vote, urban areas overwhelmingly vote liberal/democratic
rural areas overwhelmingly vote conservative/republican.
even blood red republican areas, the urban areas IN those red states vote overwhelmingly liberal/democratic.
if implemented ONLY a liberal democrat (as constituted right now) would ever get elected president- it would be virtually impossible for them to lose the election.(hillary got slightly more votes than trump, however, trump was not a good candidate for repubs and hillary imo was not a good candidate for democrats,, besides being a woman)
look at the make up of the democratic party in the house of reps,,, about 1/3rd of all democrats there are either from MA, CA or NY, democrats have major issues besides just the presidential race.