Most states that have large populations of gators need to control just like all the rest of the animals. Even predators numbers need controling just like deer.
The reason that most states make hunting them with rifles illegal and bow and arrow mandatory is because they are often times on open water and they do not want people out there with high power rifles shooting at two red glowing eyes on top of the water from a hundred yards off. Bullets will almost always roccochet off the waters surface and this could be a very bad thing to near by homes and fishermen, etc...
As far as spotlights at night go. It is incredibly difficult to sneak up on a gator in the day time. Especially in a boat. 99% of the time they will spot you long before you get remotely close. They are also incredibly difficult to spot with out seeing the two red glowing eyes. They are masters of camouflage and often times all that is visible is their eyes and nostrals. Spotlighting them at night allows you to first find them and also blinds them so you are able to get close enough to put an arrow into one.
They have to harvest a certain ammount of gators each year and this is the safest way to do it. Rifles would just be too dangerous on the water and doing it in the day would proove to be a loosing battle.
They are very good to eat. If you get the chance to try some you should definetly give it a try. After you taste gator you may just want to go hunt one some day.
There's a huge ammount of meat on a gator tail.
I hope this is what you are looking for and helps you understand the gator hunting a little better.