It could have, probably should have been, much worse. With one fatality reported due to cabin depressurization, the actions of the crew averted total disaster during the Southwest emergency landing:
Southwest Airlines Flight 1380 made an emergency landing in Philadelphia after a window, wings and fuselage were damaged. Seven passengers were injured.
Initial findings say an engine fan blade was missing. In a recording, one of the pilots can be heard saying “there is a hole and someone went out”.
The last passenger death on a US commercial flight was in 2009.
The reason these incidents, and especially passenger deaths, are so rare is that they almost never should happen. The investigation will be long (minimum is 12-18 mths for fatality incident final report) but these types of things always, short of an act of God, involve human error at some point. Expect much discussion on airline oversight and regulation forthcoming.
Also makes a reminder to actually pay attention when the flight crew presents the emergency procedures. Note as you see photos and videos in-cabin almost everyone is incorrectly wearing the oxygen masks. Attention to detail saves lives, especially in a crisis.
Amazing response by the crew led by pilot Tammie Jo Shults to get the aircraft landed safely. A profile of this remarkable aviator found here from The Washington Post.