A timely warning to the US, too - as more and more Senate votes are being decided by 50% majority rather than their traditional 2/3 (EDIT: sorry, 3/5). That both parties indulge in it should be worrying to everyone.
It was 3/5, not 2/3, to break a filibuster, and the use of filibusters had been getting to unprecedented levels. The argument above was that constitutional change should be hard I.e. require a supermajority. The Senate rules as followed recently have been requiring a supermajority for ANY change. That is unhealthy.
With Senate, the simple 50% majority is by design. That's consistent with most other bicameral parliaments out there, which also vote on a simple majority basis. Since the issues they can vote on are restricted by the Constitution, it's not really a big deal. The big deal is amending the Constitution itself, which is extremely difficult (if anything, probably more difficult than it should be).
Additionally, the Senate gives minority population states a vastly outsized vote. North Dakota and California get equal say. 50 Senators do not come close to representing 50% of the US population.
> Since the issues they can vote on are restricted by the Constitution, it's not really a big deal.
I don't agree. The U.S. Senate is very powerful; those restrictions aren't very broad.
> the simple 50% majority is by design
It depends what you mean. The filibuster, which requires 60% majority, has been part of the Senate since around the 1840s; clearly many generations of Senators thought it was important and intended that it continue.
The filibuster was always removable by a simple majority, though, so it was a self-applied restriction, not an external one. Which limited its efficiency greatly - anyone relying on filibuster knew that if they pushed too hard, it would go away.
The US should worry more about the electoral college finally breaking down and allowing the minority to control the presidency. Should worry more about gerrymandering too.