Thieving is a big part of the server, as everyone knows. People do it immediately for money, and continue to do train it for consistent money down the road. I've been thinking about skilling outfits that correspond to certain skills, and the rogue set along with black ibis instantly came to mind. Would be nice to see more outfits like this added, since skillers, and normal players, are pretty limited to skill-specific sets like this.
Edit: Other skilling sets I can think of that would be a nice addition are witchdoctor's, master runecrafter robes, fish flingers fishing outfit, lumberjack, constructor's outfit, etc. These are outfits that I can think of that are around the 2012 era of rs. Some other amazing outfits that would be nice are the later added skilling outfits, such as nimble, master camo, master chef, artisan's, blacksmith, etc.