The problem is that you’re moving from a simple easily-proven fact to something which requires two judgement calls. Any prosecutor can show that you made a trade before certain information became public, but proving that something was mismanagement (as opposed to a mistake or bad luck) or that it was a deliberate attempt to play share price games is so much harder that most executives would evade punishment even if pretty much everyone would find their actions hard to explain otherwise. White collar crimes are already enforced laxly due to the challenge of needing to prove intent in many cases, there’s no benefit to making it even easier to defraud investors.