yeah, a lot of requirements, where comparison to reality doesn't match. But at first: the question is probably not the right one for this forum - mostly opinion based... IMHO it would find a better home in a discussion board, where it can be discussed back and forth. Bitcointalk.org would be a good candidate. But I can't resist, it's too fascinating! Btw: in your enumeration you forgot pornography :-)
But their main and real intention ...
This is a suspicion, and hardly to be proved. But I am with you: war on money has started, because in rich countries there is a tremendous dependency on the taxes of less and less employees (usually in the working class). These jobs are now in eastern Asia... As this is reducing income for the government, they print enormous amounts of money - out of thin air. Along with the private banks - out of thin air. And looking at the laws for taxes, they have been changed to the advantage of the rich class in the last 35 years. In the US you are already a tax slave of your country! Even working in a foreign country, you still pay taxes "home" - I think this is what is called land of liberty and freedom. Anyhow: along with the tax issues there is also a value issue. The major currencies have all lost value over the years, roughly doubling the prices every 15-20 years (inflation). Along with extreme debts (China is holding majority of US debts), a new dependency came into the game in the last 20 years. Pressure to get an understanding of money flow is enormous, so not only individuals (slaves of the governments) feel the pressure, also the international relationships gets burdened... Pessimistic approach would be to see the end of this capitalistic system, having burnt all its fuel, and now starting to implode.
Fungibility is an essential property of money
yes. But was Bitcoin designed to be what you state? I don't think so. It was a way to improve money transfer over the internet circumventing banking systems and intermediaries. This goal has been achieved, along with a minimal set of privacy, by not re-using addresses. And certainly not buying with bitcoin over the internet :-)
Now again the reality is this stupid "HODL" idea (based on scarcity of a value), and if at the end everyone holds their coins, it has no value cause it is out of circulation. But then it is secure:-)
What you are touching is maybe Monero or Zcash and similiar, and the ideas are already exchanged in the bitcoin world. Elements Alpha sidechains is a playground for hardcore bitcoin devs, to evaluate new features, Schnorr and CT are already there. I am confident, that we'll see more coming, as requirements increase.
Security might not be the number one goal for everyone:
Looking at the way how many people used Windows over all the years, knowing it would be vulnerable, patching it all the time, and still postulating to be secure is a joke. Now all these people go into mobile, and provide their data for nothing - no need to spy on the phones anymore (hence less viruses). The vast majority of people want to have things easy and working, and not complicated to be managed. And when it comes to security, it gets tough...
Why high level bitcoin security with fungibility is not yet here (my speculation now)? Too many people just want to make "quick money". And I don't mean it negative (I might even be one of them). Too many people are not even interested in privacy. Looking at the posts in reddit, and to a certain extent here, more and more questions are exchange specific for 18year old graduates, and not technological (wow, what a complaint!). The necessity for bitcoin to provide privacy seems to decay, people don't care if bitcoin is a vehicle to transport value over the internet, cause it is more profitable to speculate with crypto currency's values.
O tempora o mores!
How we can enforce fungibility on a transparent blockchain where every
transaction is visible?
You can't - when you enforce s.th. on bitcoin, then you loose the censorship free system. No. Please. Really!
