So, I have to say - I'm actually a huge fan of the electoral college system. I would not like to see it abolished. I would like to see it expanded, and used as intended, instead of almost completely ignored and neglected and misunderstood. It is perhaps our best chance at making legitimate change to the system, since we can do it at a state level and demonstrate it's superiority.
A single state, right now, can switch to an alternate voting system, divide their electoral votes proportionally, or any of a variety of things. It gives them the opportunity to switch to far superior methodologies than any of the ones currently proposed, perhaps less obviously democratic ones but with better outcomes. That they choose to use the system the way they do is the problem. The electoral system gives the people the power to say "You can decide amongst yourselves how you're going to handle this", and the fact that they, without fail, choose the worst possible option doesn't seem to be a promising reason to require 51% support, at minimum, to even ever try something different.
In my mind, one of the main purposes of the states system is thus : to allow government to experiment, improve, and share those improvements in a way where the risks they take will not bring down the system as a whole. They are laboratories - legislative and procedural test beds, if you will. I'd like to see a constitution expound upon that in some way, and more clearly define when and how states can trump federal law (and thus allow current and future progress towards more optimal solutions), and under which circumstances federal law should have the final say (which by definition stifles legislative and procedural innovation, since you need broad compromise to enact a chance).
And then, of course, there's secondary fact that states can more precisely match the preferences of their electorates, something I think is important, though many people seem to disagree. Sure, there are racist states, and states that treat immigrants like shit, but there are also states that allow medical marijuana and gay marriage and have state-based medical systems.
Those who say the federal government should always be able to overwhelm the will of the states are saying that they are willing to sacrifice those good things, and likely any chance of those good things EVER happening, to prevent the bad. I'm not sure it's worth it. Restrictions should be clear.
I think the federal government should not be able to directly tax the people, but only the states, with the tax based equally across states as a percentage of the states wealth or GDP or income or something. Then let the states decide how best to raise those funds.