Players do have the option to work hard and gain things, its a competitive gamemode with rewards for being competitive,
if you want rewards for mindless grinding, then you have plenty achievments to do and those new weapons you can work towards.
The top100 rewards are rewards for people that try being better than the rest, the whole game is designed for casuals already.
Hell getting into the top100 while being a complete casual is easily achieveable.

The whole point you are making is you assuming everybody has the same mindset as you and your friends,
but guess what there are people who strife to be better than everybody else, and you are trying to take the single prestige that those people can achieve.