I would argue if I had a choice id rather have cat and subcat instead of CMDB. Luckily CMDB - configuration item may only be relevant to a SUBSET of Cat/Subcats
Example- A users Laptop has a broken keypad. Category- Hardware/ Subcat Laptop / Config item- a reference to the users laptop
If you have laptop mapped as a related list to usertable- you prob could avoid having it in incident as when the tech works with the customer they go to the user record and see the laptop assigned. Having it in incident however can help with searching for historical tickets regarding the this device- helping make decisions to fix/replace.
Back to the Matter at hand- Cat /Subcat- this is all about classification and reporting and assignment.. There are so many things that have no CI. You could a policy- all Subcat x get routed to Group y. You can then report on it- Inherently Performance Analytics can also pick up the data- for instance you could track cyclicly how many PW reset Incidents you get - if its 4 x more every Jan you can staff accordingly.
Cat and Subcat are easy to report on- you can study and make the classifications in a way that works for your org after studying what has come in in the past and then set up something reasonable. Agents can also use templates to speedily populate such things if they are routine.
