I think no one talks about small changes to systems for the same reason the economists don't pick up the dollar in that old joke about the efficient market hypothesis; "if it worked, someone would have already done it". The idea that bonds weren't already sold as efficiently as possible is news to me, and likely news to most people.

There's also the tendency for people to disproportionally praise "big thinking"; when we think of ideas to fix a system, the only ideas we think of (or at least, the ideas I usually think of, unfortunately) are changing the system, not optimizing the existing system. And since optimizing the existing system doesn't sound like a big, important change to most people, those ideas never get propagated. The devil is in the details, but no one wants to be a nitpicker.