Because it is an artificial, made-up term. Other terms have real meaning - chain gun, machine gun, sniper rifle, big-game rifle, shotgun, etc. Assault rifle or assault weapon is intentionally nebulous so as to be able to legally snare as many firearms as possible while conjuring up negative imagery.
Of course the AR-15 style rifles are popular. They are (compared to many other rifles) very low recoil, cheap to shoot, modestly priced (wide range of price/quality/features), and are nearly infinitely customizable. Perhaps the only real downside is cleaning. The number of nooks and crannies (particularly in the bolt & bolt carrier group) make you question your life choices. A Glock pistol or 1911 style pistol is a joy to clean in comparison. :--)
Those shootings were the impetus for the Federal Assault Weapons Ban, signed into effect by President Bill Clinton in 1994, stopping the manufacture, sale, transfer and possession of these types of firearms.
A ban which expired after 10 years. Numerous statistical studies have concluded that the "assault weapons ban" actually had no impact on crime rates. Think about that. Something that we tried, and proved to ourselves does not work, does not reduce crime in any significant way. Why would anyone advocate to try it again? Certainly not to improve public safety - we've proven such measures do not in fact improve public safety.
“cheap to shoot”
LOL!
“sniper rifle, “
Any gun in the hands of Jerry Miculek becomes a sniper rifle.
Even pistols.