Many components on a cartridge can be re-used without any sacrifice to print quality. The cartridge carcass, gears ,ink / toner containers and chips are all components which don't have any direct impact on print quality and also do not really degrade with use. These components are often re-used, which allows for a lower manufacturing cost and most importantly a far lower impact on the environment.
Worldwide, over 1 million cartridges are thrown away every day. And the majority of these are used just once! Whats even more scary, is that some of these cartridges will take up to 500 years to decompose. By using a generic cartridge with re-used components, you have reduced you direct environmental impact by at least 50%.
Please take the time to dispose of your toner cartridge correctly at your nearest plastics recycling collection center.