It's a tough call sometimes. Code legibility is important and an O(n^2) is so often fast enough (microseconds!) that a more complex algorithm may be faster for

It's a tough call sometimes. Code legibility is important and an O(n^2) is so often fast enough (microseconds!) that a more complex algorithm may be faster for the 0.001%ile and you're right that sometimes that means we should select it, because it makes the worst case still microseconds, but realistically speaking some codepaths change frequently enough that the true metric of a codebase is how easily it's adapted, understood, or modified. Let the guy with the big n eat cake, so to speak.