What? Are you saying you dad and all his friends used to use muzzle loaders before the ar-15? We’ve had bolt action at least since WW1 and semi-automatics have been common since WW2. There is no way you dad and his friends had muzzle loaders and only changed to AR-15 because of the popular crowd.
Or are you trying to say bolt action, but don’t know firearms? Because most of the old hunting rifles were old military surplus rifles largely made popular by familiarity of those who used similar in military service and the high availability of rifle rounds in common calibers.
Things like the Civilian Marksmanship Program that got old M1 Garands into civilian hands and the ubiquitous amount of 30-06 ammo that was easily accessible to hunters all over the country lead the previous era of gun owners. The current era of vets are familiar with the m4a1, but thats not available to civilians. But the ar-15 is similar so veterans tend to pick up the ar-15.
The ar-15 is also highly module. It can be rechambered in almost any caliber, has many attachments for accessories, can have the barrel, muzzle, and stock changed making it a favorite of anyone that finds a hobby in firearms. If you picked up a complete ar-15, you can change essentially everything but the lower receiver and have it be the “same” gun.
That’s why it’s popular and why so many people have one. Since it’s so popular and so common, it gets used in shootings. Not because of the traits you listed, but because the most dangerous gun is the one the criminal already has.