Ross got 19% of the popular vote in '92, which was just shy of half of what Clinton and Bush got. Pretty remarkable showing honestly. Most 3rd party candidates never get more than a few percent.
Gary Johnson has campaigned vigorously to try to get this rule changed through the courts, but apparently without much success.
In a nation of 300+ million people, having two realistic choices isn't remotely enough to cover everyone's viewpoint. Two parties is much easier for people with money to bribe. It's a good setup for average folks to lose in class warfare (and those of us who work, have indeed lost). Even the convenience store has more than just Pepsi and Coke.