The tilesheet system was implemented because loading one large image was significantly faster than waiting for hundreds of individual images to load, never mind how long it takes for a page to build when it references hundreds of different files. It also meant we wouldn't have to upload tens of thousands of individual images to the wiki, or keep track of which mod each grid image was from. The result, while having a higher barrier of entry to setup the tilesheets, results in a convenient system of templates, and scales a lot better.
@Nerixel I'm still the only one with software to automate the process of creating and updating tilesheets, and all requests for tilesheets still go through me. Anyone with staff rights is able to modify the tilesheets though, and staff often will fix typos in the naming of tiles.