I disagree. I think this is exactly the kind of question that lends itself well for a public referendum. The problem with Brexit in particular was its execution, not its premise.
For one, the people were given only a binary choice. As is clear by now (and many people knew that before), there are more than two options on the table: it is about in or out of the EU, the EEA, the ECJ, the EUCU, and about the laws underpinning the GFA. Secondly, the entire referendum was strung together haphazardly because the government didn't think it could lose, so none of the campaigners (let alone the public) knew what they were arguing for. And because of that ill-defined question, we still see major division among parliament about what people actually voted for. Lastly, the entire campaign was hijacked by xenophobic tendencies that only distracted from the main question.
Case in point would be Owen Patterson, a prominent brexit campaigner, who wanted to
1) Invoke Article 50
2) Negotiate a new deal which looks very much like the EEA plus CU, but witout any closer integration
3) Offer the public a referendum between that new deal and staying in the EU
I still find it hard to not value your own autonomy. For thousands of years, wars of independence were fought for this exact purpose. You might not value it, but I don't think you can attack others for placing value on it.
The only Leave-scenario people actually could have voted for in the referendum was a no-deal-brexit. Any other promsies were ranging from uncertain to wishful thinking.
If you told UK citizens that the choice is in fact for a No Deal Brexit and what that will mean, they wouldn't have voted for Brexit. However the population was lied to about the economic benefits and voted against their own interests.
So when the population can be lied to on such a scale, what do you find as being more democratic exactly?
And more importantly, after it was clear that Britain will not get a good deal, why wasn't the referendum repeated?