Yes, it is worth it! It's a good mental exercise for situational awareness generally. People who cannot articulate a response for this issue probably cannot articulate a response for a random attack on the street either. They're part of the group that thinks violence simply won't happen to them, ever.

Also, the cost/benefit ratio is extremely low. What's the cost of discussing possible reactions to shooters? The cost is nearly $0. It just takes your time, and the discussion is fun. The benefit is that you may be able to save your life and/or other lives one day. That's a huge benefit.

Yes, an active shooter situation may be unlikely, but most (or all) of the topics discussed on this site are unlikely. For example, it's highly unlikely that I'll have to start a fire on an off-piste snowboard trip. However, the cost of me putting together a small survival kit that can save my life is about $10. Again, the cost/benefit ratio is extremely low.

Finally, note that this site is NOT called "Equipped to Camp". This site is called "Equipped to Survive", and this is the survival forum.