Since this is a forum with a focus on survival equipment, survival kits, etc, I will probably be excommunicated for speaking blasphemy in the church of ETS, but here are my thoughts.
The first and overriding priority in a commercial passenger aircraft crash is to get out of the wreckage before it burns (or sinks). ANYTHING that slows you down in this, even for one second, is a bad choice. If grabbing a kit only endangered you, that might be your prerogative. However, any delay on your part, even seconds, endangers everyone else behind you who is trying to exit the aircraft.
Consider a little mental experiment. You are seated in the sixth row from the exit, with five full rows ahead of you. In a typical airliner, that means there are 30 people ahead of you to get out the exit. If each person causes a delay in exiting of only 2 seconds, that means that you have lost a full minute before you can get out.......
I inject insulin 5x per day and I have to admit that I probably, almost certainly, out of sheer instinct, would have grabbed my small travel bag containing my insulin and supplies (it's about the size of a lunch bag).
The overwhelming majority of survivable crashes of airliners happen at takeoff or landing. In nearly all cases that means you are in or very near a city. If you survive the crash and successfully exit the aircraft, you will shortly be in a hospital with all the insulin and other meds you need. On the other hand, if grabbing your small travel bag keeps you from escaping in time, you will shortly be in a morgue, and have no need for your insulin supplies.
I have not had to evacuate a plane quickly, but I would almost surely grab the small backpack that I stow underneath the seat in front of me.
See comments above.
Yes I am crazy I guess, but I have gone down in 2 helicopters and 1 airplane (all on military operations).
The OP is about a commercial airliner incident at a major airport. Military operations, helicopter work in remote areas, bush flying in small aircraft, etc all present different problems.
I contend that when flying in an airliner, any crash scenario will almost invariably be at or near a large airport. Help will soon be at hand, and ground survival most likely won't be a big issue. Your overwhelming priority in those cases should be to survive the crash, and to get out of the aircraft quickly.
In other types of flying, needing gear to survive on the ground after the crash might become a bigger possibility. However, even in those cases, getting out of the aircraft alive is still the first priority. My own approach when bush flying is firstly to dress for conditions on the ground, and to carry key items in my pockets. Other survival gear should also be carried, and if the aircraft doesn't burn or sink you can go back in a retrieve it when it seems safe to do so, but EXIT THE AIRCRAFT FIRST.
First and foremost,
ALWAYS FOCUS ON GETTING OUT OF THE AIRCRAFT AS FAST AS POSSIBLE! While other considerations are also important, anything that interferes with escaping the crash (even for a couple of seconds) is counterproductive. The best survival kit in the world does you no good if you are already dead!