There was never an intentional move to create a "two-party" system. That's an accidental byproduct of the winner-take-all system, which tends to reduce the number of parties. But we've definitely had some time periods where there have been 3 or 4 viable parties.

But that's not what I'm talking about. What I'm talking about is the divide between the Senate (2 senators per state) and the House of Representatives (based on population), and the inclusion of techniques like the filibuster. It's harder for one party to get a majority in both House and Senate than it would be to just get a majority in a single parliament. It's even harder to get supermajorities in both. It's even harder to also get a friendly president at the same time as all of those other things. This means that there's almost never a time when one party can just ram through its whole agenda. There's almost always gridlock.

From what I've seen of single-house multi-party systems (like parliamentary democracies) there's a lot more compromise, which is a good thing, but there's also a lot less gridlock, and that's a bad thing.

It's actually a good thing that successful bills tend to be either issues the vast majority of the country agrees on, or else very watered down.