> It shouldn't have been a vote without requiring a Supermajority
Works well on the internet. Bad idea in practice. You have to remember that the government didn't want a referendum. They wanted UKIP neutered and the issue put on the backburner.
If there had been a referendum with anything other than a straight majority, and Leave won a straight majority, all hell would have broken loose. It would likely have split the Tory party and made Farage the most important politician in the country.
Similar argument goes for a 3rd option. They didn't want a sensible alternative, they wanted a "put up or shut up" straight fight. Same as had occurred in Scotland. These referenda (and the AV vote before that) were to put constitutional issues to bed not to find alternatives.
It shouldn't have been a vote without an actual /plan/. "Would you like to 1) no change or 2) SUMMARY OF A DETAILED PLAN INCLUDING E.G. WHETHER THE U.K. REMAINS IN THE SINGLE MARKET OR THE CUSTOMS UNION OR HAS A HARD 1980s STYLE BORDER WITH IRELAND ETC" is one thing. "Would you like 1) no change or 2) some vague thing everyone can project their desires upon and scrawl fantasies on the side of a bus" is not a great way to make policy decisions.