As with most things administrative or beurocratic it takes a tragedy to force a paradigm shift. Sadly those men gave their lives to try and improve things for the future generation of LEO. Be it better ammo, better hardware and better tactics they sacrificed a lot for the next batch.
I doubt that we will ever know what truly cause the situation to go as sideways as it did, but I'm 100% certain it isn't just one solitary thing. It's most likely an issue of poor choices, compounded by poor equipment compounded by poor training compounded by an opponent who was unimpressed by the FBI badge. Truly a shit sandwich, with which they did the best they could.