You have all covered this well. From my experience I can add only that I see a symptom that is rampant throughout aviation that I can describe in two points:

1) Improper (or not thorough) training. I honestly think that preflights and A/C condition in general is not stressed enough. A possible reason might be that since A/C are mostly much more reliable now that even 30 yeears ago maybe some of the newer instructors find it (falsely) unnecessary to check every little detail or at least as often as should be done. I am sure all of us, even 20,000 + hour pilots, need to constantly watch out for complacency. I will admit that I have been guilty and just by the grace of God got away with it.

2) I may kick up a storm here but....... Ultralights. I think they are great and have their place. Having said that I see too many people buy one, get a couple of hours of "instruction" and just take off and fly. three deaths here in this area in less than a year directly related to lack of knowledge of even basic aerodynamics or the physics of flight. I know there will be those that will jump on this and defend U/Ls. Trust me, I have heard all of the arguments but I have also been first on the scene of the results. I am not saying that they cannot be safe and fun.

How do U/Ls contribute to GA casualties? Well, it seems to add a sense of "flying is easy, and anyone can do it". Case in point: I know first hand of an individual that flew U/Ls for a few years then moved up to full scale. Even though he went through basic training, ground school and such, he always had the attitude of "this is no different than my U/L, just faster". Poor preflight was just his way before and apparently his instructor did not emphasise it enough (or he just knew better). 3 weeks after receiving his license, dead at the end of the runway. Water in fuel. I am not saying that the average Joe is not smart enough to do basic stick and rudder stuff. What I am saying is there are a lot of folks out there not taught a healthy respect that any flying machine can kill you. I know GA is fighting for new converts every day and we need to pass on the heritage of the freedom of flight and freedom in general but maybe EVERYONE needs a little lesson in the sanctity of life (your own too) and to slow down, observe and THINK!