The electoral college was set up to give small states a chance to be relevant during an election. If the only thing that counts is the popular votes, candidates would never go to the smaller or less populous states.
I don't know if that would necessarily be the case.
If this passes in enough states, then the candidates will no longer care about state vote totals, but instead about three things:
1. National vote totals
2. Areas of the country where the vote is in flux
3. Cost of electioneering in particular areas of the country.
Smaller states will most likely have cheaper electioneering costs (e.g. TV ads, etc.) Smaller states are also more likely to contain more swing voters. So more votes could potentially be shifted with less money if candidates spent time/money in those areas.
One good thing about this would be that no one would have a reason to not vote until the last votes had been counted in Hawaii. Because the overall total is what's important, any vote in any state could still matter.
The worst thing about this is that all of the states use different voting methods and procedures. The main problem with what happened in Florida in 2000 is that there was a great diversity in how votes were tallied across the state. If this were to be workable then every state would have to have the same, or very similar, voting/tallying procedures.
Imagine how the libs would feel if it was determined that we needed one consistent voting system across the nation and Diebold won the contract!
You make that sound as if it's a bad thing.