No one asks you to make your btc addresses public. You can keep it as secret as you will. You can always choose to generate one-time receiving address if you want. But is there any reason to stop others to use one address as their public address if they think they don't mind?
Because reusing addresses makes it open to everyone, not just the relevant parties you'd like (or have been ordered to) disclose them to. Worse, your lack of privacy make everyone you transact with and everyone they transact with less private. Your comments about "always choose" are empty promises in the face of proposals to have black and white lists which will limit your ability to transact, and empty in the face of privacy losses created by people who you've transacted with.
I can turn everything you've said right around there is nothing preventing you from privately identifying yourself and registering your addresses. You can always do this and the parties you transact with can to. Nothing about requiring privacy preserving behavior in the public network prevents you from separately having information disclosed about you, nothing can prevent investigations from happening. But the converse is not true, the lack of privacy in the public network very easily prevents people from choosing to be private at all, and it very easily can make Bitcoin worthless as a money like good.
Could you provide a concrete example to explain why reusing addresses by A will affect B if B always carefully choosing address. and how both A and B never reusing addresses prevent it? I'm still not so clear about it.
Since the drawbacks are very apparent, IMHO you need a very clear explanation about the benefit and why the benefit is far more important than the drawbacks.