In order to appreciate the reasons for the Electoral College, it is essential to understand its historical context and the problem that the Founding Fathers were trying to solve. They faced the difficult question of how to elect a president in a nation that:
*was composed of thirteen large and small States jealous of their own rights and powers and suspicious of any central national government
*contained only 4,000,000 people spread up and down a thousand miles of Atlantic seaboard barely connected by transportation or communication (so that national campaigns were impractical even if they had been thought desirable)
*believed, under the influence of such British political thinkers as Henry St John Bolingbroke, that political parties were mischievous if not downright evil, and
*felt that gentlemen should not campaign for public office (The saying was "The office should seek the man, the man should not seek the office.").
How, then, to choose a president without political parties, without national campaigns, and without upsetting the carefully designed balance between the presidency and the Congress on one hand and between the States and the federal government on the other?
I'm not going to try to argue intent, others can no doubt do that better than me. The result, whether they wanted it or not, IS a 2 party system and has been almost right from the beginning. We've had 1 political party collapse (the Whigs) and be entirely replaced by Republicans who immediately became the second leg of the two party system. And it didn't happen at the Presidential level first, and no Libertarian Party, Constitution Party, or any other newfangled Party people dream up this time around is going to be even remotely competitive or make a single iota of difference.
So long as there is no opportunity for coalition government with multiple party's, there will be a 2 party system with both aiming for 50%+1 of the vote for the win.
The founders may not have WANTED a two-party system, but the whole first-past-the-post, winner-takes-all election system we have mathematically GUARANTEES that only a two-party system is viable. You can’t have anything else with first-past-the-post, winner-takes-all voting.