What it will do is favor states that aren't swing states. Which is the large majority of both states and electoral votes. Texas would be a huge winner in a transition to the popular vote because it has so many people in it, and is currently almost completely ignored in Presidential politics. Most of the South is in the same boat.
And as I'm looking at the map right now, let me point out something extraordinarily dangerous about the current system: Florida has the largest number of electoral votes of all the swing states, and demographically it's full of retirees who don't live in the same zip code as their children or grandchildren.
Even if you're an arch conservative cotton farmer in Alabama, how does it help you that decisions about whether we send your children to college or to war are unjustifiably disproportionately influenced by a bunch of retired Giuliani-era East Coast elites with no connection to the future? Wouldn't you at least want to be able to cast your own vote and have it mean something, rather than blindly assuming that newly Floridian retired state employees from Jersey and Queens will necessarily have interests that coincide with your own?
I think I said that. That's not the only thing it does. When it comes to Texas there's the idea that they might get a bigger share of the ad cash but this is in conflict with generally worse chances for the GOP candidates.
A better idea for a red state looking for ad cash would be to team up with one or more blue states of similar total size and move to an honest proportional EV system. The cash wouldn't be diluted as much either (at least initially).
By 'honest' I mean not the sorts of hijinks the GOP is trying out in VA (and elsewhere) where Obama would win the state vote and lose 2/3 of the electors. The problem there again is sooner or later some state get's kingmaker power by changing back to plurality = all evs.
Again, it's not about parties, it's about policies. The long-term average will always be for each major party to win about half the time because if they don't they'll change their policies until they do. The question is what policies they'll adopt in order to do it -- and if your vote doesn't count, whether you're Texas or New York, your voice isn't the ones they'll be listening to when deciding what policies to adopt. What good does it do a Texas social conservative to elect a GOP candidate like Mitt Romney?
I'm not sure what your point is. Where he differs from Obama, Romney's positions are nigh-universally closer to those of Texas social conservatives aren't they? What is the biggest issue for Texas social conservatives? Abortion? What office that a Texas social conservative votes for has more impact on the future of this issue than POTUS? Would Romney's Supreme Court nominees presumably be better or worse than Obama's from the POV of Texas social conservatives?