[CobrastanJorji]

The main downside to switching the hash function is that, when explaining why developers should stop worrying about hash conflicts, we'll need to calculate a new analogy to replace the standard, 180 bit "every member of your programming team being attacked and killed by wolves in unrelated incidents on the same night" scenario.

[deathanatos]

That analogy presumes that the hash function's output is uniformly random; when you know how to manipulate it s.t. its output is not random, then obviously it doesn't hold.

The question of accidental collisions is still relevant, even with SHA-256, and the answer is still the same: it's so vanishingly improbable that it is assumed to be impossible.