This is basically a violation of the robustness principle ("be liberal in what you accept, be conservative in what you produce"), but I doubt there will be much improvement on this front seeing as tokens are fed back into the model. A succinct phrase is a compressed form of a longer sentence that expresses the same idea, so from the perspective of having to feed the model's output back into it, more tokens presumably work better by providing a greater of surface area for processing, so to speak. This is just my intuition, however.

That principle deserves to be violated. Invalid input is invalid. Rather than everyone everywhere trying to handle it and producing subtly different implicit extensions of whatever standard they’re nominally ingesting, everything should reject it so the producing system is forced to correct itself.