Well, the referendum was non-binding, and with that in mind these MPs are doing what their job is in it. You may not like what they choose, but in that case what you actually don't like is representative democracy, as the MPs are literally doing what "representative democracy" says on the tin. Wasn't it about "bringing power back to parliament", anyway?
People might have more of an idea of what they are voting for now, if a referendum is conducted again. Leave voters weren't choosing between a deal and no deal the first time, and if they did have a deal in mind, they had no specifics. It has taken so long to "Leave" precisely because of this problem - the EU itself was ready to accept the withdrawal agreement last year.
Funnily enough, the EU's structure is actually more democratic than the British one when you analyze each of the branches.