I don’t believe bitcoin was ever designed to be a privacy coin. The whole concept behind bitcoin was a way to transact with no intermediary with the concept of an open blockchain so any one participant can verify transactions. It’s inherently open by design.

Privacy is a job best suited for coins designed with it in mind. Monero, zcash and pivx just to name a few are great for this task.

Bitcoin, to me at least, is best suited as a store of value. More likely to replace the gold standard than to become an every day transaction method. You don’t buy apples at the store with gold just like I wouldn’t buy gas from the gas station with bitcoin. I see bitcoin as more of a safe haven asset.

This doesn’t really address its fungibility, that is definitely an area of concern but that has more to do with regulation and policy than it does the underlying asset itself. If your problem is other users being able to see how much you have and where you send it use a privacy coin that isn’t susceptible to this. If your problem is exchanges, on/off ramps locking out assets used for illicit reasons that’s merely regulation and policy that needs to be changed.

KYC and AML registrations are unfortunately a necessary evil in order to keep crypto and blockchain as a viable alternative to traditional fiat.