No Stupid Questions

Because it's not a small thing to change. You're basically overhauling everything if you wish to transition from a monarchy to a republic, because it's rooted in everything.

The names of the governmental positions, and possibly their responsibilities would need to change, as would official documentation, the money, the flag, the national anthem...

You could hardly call yourself a republic if your passports are still carry the authority of the monarch, and your national anthem prominently features the King.

It only gets more complicated if you're a former colonial power, since they may also be affected, and have to change everything as well. If the UK decides to ditch the Monarchy and become a Republic, Australia and Canada would need to follow suit, since it would be silly for them to have references to a monarch that no longer exists, or a GG who's meant to be representative for a position that no longer exists.

Either that, or there will be a political/legal headache deciding whether they become the new inheritors of the monarchy, since the parent is gone, or would they be also need to make the same changes (see above).

Monarchs are like cardboard boxes. Someday they'll be useful again, you just know it.

These comments are proof that Robespierre didn't go far enough.

Because some people never grow up and still want a daddy/authority figure to tell them how to live.

That's why orginized religion or other authoritarian fetishes exist.

Keeps the conservatives somewhat placated.

A lot of good points here about pros and cons when considering republic vs constitutional monarchy. I was myself against the idea of monarchy for quite a while, but I realize it's mostly because I was living in the UK at the time and was exposed to how normal people are treated compared to the upper class. In addition, though the British royal family doesn't have any power on paper, they have vast connections in all parts of the government and private sector with many ways to influence things. Also, the UK was until recently a two party state, which meant almost total power to whichever party won the election.

Scandinavia doesn't have as much of a disparity between social classes (even counting royals), and what I see here is that the monarchy provides a stability and continuity that we wouldn't get with a republic. Anyone can lie, cheat and bribe their way to getting elected president, but when you have a dozen different parties with different policies passing laws with a monarch as an anchor, it works out pretty well.

Not going into civil war. Basically that's it.

Democracy but don't destroy previous institution because some people would actually go to war over that.

I think eventually they all will fall. When people just stop seeing the point.

Most constitutional monarchies got that way due to incremental change generally caused by political crises. Switching from a monarchy to a republic usually done as a response to one of these crises; no crisis usually means the monarch keeps the crown.

You also have an issue of what to replace the monarch with. Most constitutional monarchies have parliamentary systems of government where the legislature has supremacy. However, you still need a supreme executive to run a government when the legislature fails. The process of picking that person is very politically important and had inherent risks to it. For some countries, keeping the monarch as the on/off switch is easier than dealing with the headache of choosing a President.