When I bought my CEROS, I also bought a box each of 80, 120, 180, 220 and 320 grit Abranet discs. I'm not sure that I needed the 320, but I bought it anyways. When I got home and opened the tool, I found a package of a sample pack of abrasive discs - one of each Abranet discs from 80 to the top (400 or 600 grit) as well as one each of the 40, 60 and 80 grit Abranet HD discs. Being able to try them eventually led to my decision to purchase a box of each. Actually, I wasn't even aware of the HD discs until I found them in the box.
Bottom line: I don't think it's necessary to include a supply of abrasives with the tool, but I think it was a good marketing idea to include one of each grit - especially the ones that people might think they would not use.
Shane: To directly answer your question, looking at the abrasives available for the RO90, I would like to see the following grits of round Granat provided with the sander: 40, 60, 80, 120, 180, 220, 320, 400 as well as between one and three triangles of Granat: 120 for sure, perhaps 80 and 180 as well.