When considering the Monty Hall problem, you must first discard the actual behavior of Monty Hall on Let's Make a Deal. The problem is stated clearly, and excludes any distractions or alternate monetary offers. With the two sons problem, we should make the common-sense assumption that the odds of bearing a boy is 50%. Stick to the problem at hand, and not a related problem.
Over-thinking things tends to be the cause of many problems. The Monty Hall problem does not have a deceptive host, it has an automaton doing what is explained. Those sons aren't arranging themselves in clever families to confuse the issue.
The other problem is confusion between chance and reality. People expect a coin to come up heads exactly half the time it's flipped. They include cases that could not happen in the terms of the problem, like including families with 2 girls in the odds of having two sons. Or, they discard information from memory that still applies, like believing that each remaining door has a 50% chance of having the car.
The final problem is that those who have solved the riddle forget that it's supposed to be puzzling. Not everyone is as smart as you. Not everyone has a logical mind. If everyone could think things through perfectly, then many interesting games would be boring. Or perhaps we'd just over-think everything, and we'd all be as annoying as Vizzini.