That should already be possible with mods, I think. For example, you could make a chassis that doesn't have an "arms" slot, but instead an "arms_low" slot, which would only accept D-rank or below arms gear (you'd need to edit the parts as well, so they can be put into the new created slot).
It would be quite a bit of work to do it with a mod though, as it needs rewriting all the mods and parts already in the game, as well as all the bot models and parts added by the mods you want.
In the end, your proposition would give more variety to bots, instead of just having all bots with the same S-rank parts in the end. So I think it would be interesting. But it would also limit how people want to develop each of their bots (for example if they prefer X or Y looks). Not sure which would be best for the game...
Good point that it would limit people to what chassis (appearance) they'd use for what purpose. It would be a shame if one appearance would be too purpose-built when someone might really want that look for some different role.
Return to drawing board..
Purpose built CPU's perhaps? Or more emphasize on energy use for the various roles and powercore limitations? I just figure that a medium grade powercore should allow for some combinations of "light"roles, like Clerk + Bedroom Toy, but not Shopkeeper + Bedroom Toy. And with purpose built mods, we could get into the realm where some powercore or CPU could run one role more efficiently, allowing for combinations that could otherwise not be achieved, which could be an alternative to purpose built mods that add benefits to specific roles.
Now, say each role costs energy, for example:
Bedroom Toy: 1 energy
Clerk: 2 energy
Techie: 2 energy
Shopkeeper: 3 energy
So, we could end up with 2 powercores of the same grade, say, grade C, both providing (for example) 4 energy, but one could have a bonus of "Shopkeeping costs 1 less energy" (allowing for more combinations with other roles), while another could have a bonus like "Bedroom Toy costs 1 less energy".
The Shopkeeping powercore would allow for the combinations Bedroom Toy / Shopkeeper, Clerk / Shopkeeper and Techie / Shopkeeper
The Bedroom Toy powercore would allow for Bedroom Toy / Shopkeeper, Bedroom Toy / Clerk / Techie (if the CPU keeps up and allows for 3 roles)
So, in general, some variation in diversity on top of linear progress. And yes, if we get more roles, and some of them being more demanding, I could totally see even the top powercores with optimal specialty just barely having enough juice to run one heavy duty role and one medium duty role together.
