Long before Brexit, I was bemoaning the bad effects of direct democracy in California for constitutional amendments that pass with a simple majority. A good amount of the dysfunction in California is from these sorts of propositions that can not be overruled or modified by the legislature. And the public debate about them is largely divorced from their actual content, quite frequently. You still encounter people that think that Prop 13 is a about letting grandmas stay in their homes in retirement by sheltering them from any increase in property taxes, but it is a much much larger handout to commercial real estate and investment properties than it is to grandmas, for example!

Even a slightly higher threshold than majority vote would be good for direct democracy. And constitutional amendments should either have a higher bar, or should automatically expire after X years unless there's a second vote to verify that the change should actually stay in effect.

I tend to vote no on all ballot propositions automatically due to the bad effects of permanent changes being far too easy with too little substantive information provide to voters.