I agree with almost everything you said. Almost exactly right. Proportional allocation of electoral votes by states by popular vote (not by CD's which sucks for the reason you mentioned) does have its merits though (it would not lead to massive litigation, maybe in a couple of states if the electoral count were near even). Granted, it would lead to the candidates spending most of their time in the high population states. That seems appropriate to me. In short, swing states versus metro areas is not very persuasive as a policy argument. Why should swing states be so special, just because the geography happens to lead to a close partisan split? But it is not worth the bother. The electoral college as constructed in close enough. The idea is to get a quick result, by the rules, provided the popular vote is not way out of line. Close is good enough in horse shoes and electing a president.
I agree that a proportional electoral system based on each state's overall popular vote would be far less objectionable than one based on Congressional Districts, for reasons previously cited. Even the better of the two proportional schemes bothers me, though. State lines should mean something (maybe the old "States Rights" Southerner coming out in me), and the loss of the winner-take-all system would surely deemphasize the importance of the states.
Anyway, we're probably beating a very dead horse. I can't see many individual states going to such a system voluntarily; anyway you slice it, they'd be diluting their electoral clout (which is why I am perplexed by the choices made by Maine and Nebraska, and would not be surprised to see either or both states end their little experiments, which in any event have had no effect to date since the Dems have taken all of Maine's EVs, and the GOP all of Nebraska's). So the only way we'll see a proportional electoral vote system happen is via a Constitutional amendment, which is about as likely as me being named the next Pope.