Shooting The First Responders in The Face Is Bad
Trading hostages can buy you a significant amount of time before SWAT arrives. Which also means longer before they ramp up the difficulty.
If someone shoots the cops at the start, the negotiation phase ends immediately and they charge in.
There is even a perk that can effectively double the amount of time hostages give.
So at the start, even if you’re going loud, secure as many hostages as possible.