Israel had proportional voting with a 1% electoral threshold (given there are 120 seats in the Knesset it's almost the natural threshold). They eventually raised the threshold more and more (3.25% now I think) because of the hyper-fragmentation which meant niche parties holding the coalition hostage.
The degree to which a given electoral system represents voter preferences is highly election-specific. People are also usually not polled on their detailed preferences so it's hard to empirically determine which one is most likely to maximize the representation of voter preferences in a given country.
Also the complexity of optimal voting strategies across electoral systems is different. An argument can be made that the simplest is the best. Say last year in Poland the mainstream consensus was that there's going to be a big coalition of all the parties against the biggest one. But some of the minority parties under-performed while the big one overperfomed giving the big one majority rule with just 37.58% of votes. If you'd redo the elections even the same week you'd probably end up with a much different result.
If the U.S. electoral system easily allowed for other parties to exist and thrive (such as with a proportional representation voting system for Congress, which drastically increases how well people are represented in Congress, and could lead to much less "gridlock") then this wouldn't be an issue. Because those 91% of the people could easily ignore the Democratic and Republican candidates if they were terrible (which seems to be the case this year), and just vote for another party's candidate in the general election.
And they could very much still do that. The problem is there's both a legal and unofficial collusion between the two main parties to control the elections in various ways (such as making the rules for who gets to debate), and between them and the media, who normally completely ignore other candidates, and don't treat them nearly as fairly, so their chances greatly diminish.
There are a lot of things that could be done to fix this. But people need to support politicians willing to overhaul this system.
Larry Lessig (on who the DNC changed the rules mid-game so he doesn't get to make his case in a debate) had some great ideas [1], and so does the Green Party [2].
Jill Stein also supports ranked choice voting, and I believe multi-winner ranked choice voting, too, which is a form of proportional representation [3].
Unfortunately, you're not going to hear about all of these ideas from a media that has a vested interest in maintaining the status quo, and you'd have to rely heavily on the Internet and social media to grow this movement (and do it before Google/Facebook/Twitter start ramping up their censorship to help their favorite candidates, as we've already started seeing them do).
[1] https://lessig2016.us/the-plan/
[2] http://www.gp.org/democracy#demFreeSpeech
[3] http://www.fairvote.org/proportional_representation