There is a lot of speculation by folks here being stated as fact. You really should figure that you have not gotten all the facts, or much of any facts form a news story..
From what I have seen so far there were mistakes on both sides of that door and the entire series of mistakes ended up in a tragedy. Breaking that chain of mistakes at any point would have rendered a far different outcome.
This was not a hot pursuit situation. The Deputies lost sight of the suspect for some time. Enough time that they ended up finding the bike at a later time from the original incident. Since this is not a hot pursuit there is no need for breaking the door, nor was there any mention in the article that the door was forced by the deputies at the scene.
This was a classic case of get a surveillance team out to the apt. complex and observe. There is no immediacy or hazard like an active shooter or hostage situation. Use plain clothes folks to watch then follow or apprehend the suspect if he comes outside.
The deceased should never have opened the door at 1:30 AM just because someone knocked. If he felt threatened enough to bring a firearm to the door he should have turned on the light, looked through the peep hole (if any) or looked out the window to ID the person(s) knocking before even thinking about opening the door. He should also have called 911 while still inside the closed locked door to report the knocking and request assistance in determining wtf was going on. Last mistake would be (assuming the news has it correct) to bring a gun to the door and have it pointing to the person(s) on the outside before determining if there is A. a real threat and B what kind of threat there is. and finally C. if you think there is a threat outside the door, do NOT open it if you are on the inside behind a locked door. Stay put, out of the deadly funnel, and call for help.
The holes on the door are angled. That is reasonable to expect as the deputies are not going to stand directly in the front of the door when they figure they are going to confront a suspect. Hell it's standard practice to stand to the side period when knocking on a door anyhow. Just a good habit to get into. The one on the hinge side of the door knows already they are in the first line of fire to be available if the door starts to open.
The person inside the door probably is likely to open the door only a bit and be standing to the side so they can look outside without having to fully open the door. Would you stand in front then open it wide for an unknown knock at 1:30 AM? Having a gun pointed to the outside as you open the door leaves little to no other options but opening fire for the deputies on the outside once the threat of the gun is noted.
Those two situations would set up the shots for angled fire into the opening.