I asked this before, I think.
If not the President who nominates (and whose nominees must be passed through congressional committee, and then approved by both legislative bodies -- who represent the people), how should the Supreme Court justices be determined? By the way, since all three branches of government participate in the process, I don't know how separation of pwers is "removed".
Your answer must offer an ironclad guarantee that whatever process you suggest cannot be politically influenced in any way, shape or form.
Thinking about it, I think you'll find that there is no way. It's not an inherently flawed system. It's a system that becomes flawed if those in it ignore their oaths and abuse the trust placed in them.
Now if you want to argue that ethics rules aren't remotely stringent enough, or SC justices shouldn't be appointed for life, or there should be more of them, then those are different issues that could bring about postentially positive change.