"Monero’s privacy features can be absorbed into the Bitcoin protocol whenever Bitcoin decides it wants to"

I think that's the biggest flaw in your thinking. Monero has this built-in from the start and everyone using it knows it and supports this approach. It affects how legislators can manipulate the coin because they can't, it will keep on living. It already affects the true value of the coin with all privacy included, because you can see how exchanges are unwilling to list it or are delisting it if they already did so, so there are no (or hardly any) institutions or billionaires manipulating the price because of the high risk factor of losing their money. You're forgetting that people in power nowadays are brainwashing us to accept that a wanting a fundamental right like privacy equals you're doing criminal activity or have plans to do so. There are A TON of reasons why bitcoin will never include such strong privacy features, because there are so many factors that influence this decision to make it possible, and the dominant reason you see that matters to btc holders (or any other crypto token for that matter) is NUMBER GO UP. Privacy is not a number go up reason. So it's not a tech issue, it's a people issue