You cannot have privacy in an open ledger, that's a completely different protocol. See Monero if that's what you want.

The problem with making it "better" is that the risk is a couple orders of magnitude more dangerous than any incremental improvement you might make.

The single biggest threat to bitcoin is that they will soft-fork in some new opcodes that bring with them unintended consequences. Think taproot, but worse.

That's all it will take is one opcode that someone figures out a way to exploit.