Perot didn't win a single EV.
And Clinton won a clear majority of the electoral votes.
Why would there be any need for a "runoff"?
For the same reason anyone has a runoff election where they are mandated by law. A runoff election occurs when no candidate garners 50% of the votes, just as happened with Ted Cruz’s race in Texas. It’s an absolutely necessary step to ensure that a person’s vote means anything at all. Otherwise you can have a Satanist win an election with 11% of the vote if there were 9 other candidates that didn’t exceed 10%. Unless you have a runoff in some form, there is no way to know who the majority people want to elect.
Take the presidential 1992 race in Pennsylvania. Without a runoff, there is no way to no if more than 45% of the voters would have taken EITHER Bush OR Perot over Clinton. A runoff between the top two vote-getters could’ve resulted in a 55-45 split for Bush over Clinton, which would be the true democratic result that reflects the will of the people for who they wanted to be president. Why in the world should someone be elected president if 55% of the people would’ve ranked a single other candidate higher? You don’t know if they do or not without having a runoff.
William Clinton 45.15%
George Bush 36.13%
H. Ross Perot 18.20%
And with a properly formed ballot, an instant runoff can be done that doesn’t require people actually going to the polls again. But even that is a worthwhile expense to pay to ensure the integrity of the democratic process.