"I'm just interested in why there was a ban in the first place, and two, why do you need such a weapon?"
Okay, number 1: These firearms were banned because several isolated lunatics used them to kill people in a few mass-killing incidents. This terrified the more moderate soccer moms out there and made the idea of a ban palatable to politicians who previously would have rejected such a thing. Also, the anti-gun Left was WAITING for an excuse to get even a SMALL victory in their mad rush to ban anything with which a citizen could plausibly defend himself.
Number 2.: These weapons, being based on military firearms, are perfect for the defense of one's home, the taking of small game, or the defense of one's basic liberties against tyranny. In essence, they are simply perfect as all-around, general purpose rifles. They are, for the most part, the most reliable, easy-to-shoot, inexpensive(pre-ban), and robust firearms out there. Plus, their ammunition is and remains cheap. Oh, and they're great good fun to shoot, too.
Let's be clear...the 1994 ban covered not the weapons themselves, but certain features thereof...like flash supressors, pistol grips, folding stocks, and bayonet lugs. Their magazine capacity was limited to ten rounds, versus the 20-30 of preban models. What most folks, myself included, object to is the "camel's nose" that this represents. That, and the overall idiocy of it. Seriously, banning a gun because of a bayonet lug?!? Not even the psychopaths responsible for the bans ever used bayonets in their madness! So desperate were the gunbanners for a "win" that they abandoned any rationality.
I hope that this helps. Need to know any more?