Sir John said recently that the MPs must make the final decision on Brexit because the voter is not informed enough to make such critical decisions. Are there such cases in which only our representatives can be shouldered with such responsibility?
There are several problems with this assertion:
It assumes the MPs are somehow uniquely qualified to make decisions by virtue of being MPs.
In reality, the main and only skill an MP possesses is to be elected to the position. They might have other qualifications but that's not a given at all. The voters don't pick "the best person in the country to decide on Brexit" (even assuming that's possible). They pick "The best person able to convince them to vote for them".
MPs are supposed to honestly and truly represent the interests of their voters.
However, that is not a valid assumption to make.
In some cases they simply don't bother, picking interests of one subset of voters over another (in the simplest case, when close to half their voters are supporters of opposite party, but it can be less drastic than that in other situations). The most lopsided case of this is for example corruption, where a representative picks the interest of a paying party over the voters'; or their own personal interest.
In other cases they may genuinely want to truly represent voter interests, but objectively can't - they either have their own biases preventing them (globalization is seen as universally good for most of governing class), or they simply don't know the correct answer, often because "correct" answer isn't easily knowable - see the next bullet point.
Even assuming they are somehow "better" than average voter, MPs are human.
Therefore they just as incapable of comprehending what a "correct" decision in a complex chaotic system is as other people.
The problem is that the consequences are not really well understood by anyone, nor even easily attributable in post-analysis. As an example, almost entire ruling class predicted immediate and deep economic crash in the unfathomable impossible occasion that Donald Trump were elected President.
Philosophically, this approach logically leads to an assumption that absolute tyrant is the best possible form of government.
If a representative knows better than scores of plebes, it's not unreasonable to assume that an enlightened philosopher-king (we can even make them elected, to ensure "truly the best king" rules) would know even better than scores of representatives based on the same logic.
In some cases, you might even be right and end up with Peter the Great or Cyrus the Great or Deng Xiaoping. Or, you might end up with an atrocity like Nero, or Louis XVI or a useless-burger like Brezhnev. History shows that the former is far far less likely (and even Peter the Great made great big mistakes, for all his brilliance).