I don't think it was a poor idea at all.
You don't want California and NY (or Texas and Florida) to dictate policy to the rest of the country.
By forcing politicians to look for support throughout the country, it tends to be a force for moderation (and communication).
The fact that we've fallen into an extremely partisan cycle doesn't change that.
The electoral college is still dominated by the populated states, and the "empty" states are split between parties (see NE v Northern Great Plains.
The reason the Democrats get the popular vote (by small margins) but lose elections is they gave up on "Red" states decades ago, and starved their local political organizations - hopefully they've learned their lessons and are building grass roots support - b/c Texas and Florida will be in play in the future, the way NC, Georgia and Arizona have been in play. But you can't just fly in every four years.
Gerrymandering is also overblown, most is simply due to Democrats focusing on urban areas and writing off exurbia and rural areas - but as Walz shows - with the right policies and candidates, those are in play. That concentration of Democratic voters means that even "impartial" redistricting would result in numerous one party districts.
The problem for the Democrats is this would require a commitment to tone down the rhetoric, change the focus from race to class, and drop strident calls to protect "rights" and replace it with a pragmatic programs that would help working class whites as well as minorities (who would disproportionately benefit from any program that helps the working and middle class). And that would be a dramatic shift in emphasis by the Party.
A true majority party in America would be strongly centralist, Progressives are 15%, Hard right 30% or so, 55% spread between moderate Republicans, Independents and mainstream Democrats.