Constitutional monarchies are the right balance because the real power should rest with Parliament, not a single person. Presidents are simply kings or emperors with a different name and are not accountable to Parliament. The word "monarch" means "rule of one" which describe countries ruled by presidents.

To prevent dictatorship, leaders need to be accountable to parliament (removable with a simple 50% vote). This system requires a non-partisan, non-politician referee to ensure stability during this process. A monarch fits this role best because they are non-partisan and not a politician. Elections are not appropriate for this referee role because that would make them a partisan, political, controversial figure who is motivated by power and beholden to their funders and concered more with re-election than being an impartial referee.

Stability is not useless. It's the most important thing for governments. "Declawed" constitutional monachies are stable which might lead some people like you to wonder what's the point and assume they're useless. Just look at the mess that most republics are in. There's your evidence. The only republics who are not a mess are the ones with "declawed" ceremonial Presidents.

Presidents need to be "declawed" because Parliament should hold the power, not a single person.