imj: Did Castle ever ask ROL to make a 32bit OS? You know that they didn't? How, pray tell, did you happen by this gem of factual information? Most RISC OS *users*, never mind hardware developers, had been demanding a 32bit RISC OS for a long time.
It seemed ROL wanted paying to do this work then take royalties. That defies normal business sense. ROL should have created the product and then sold it. Would you expect Castle to build a machine and then hope that ROL could be persuaded to produce 32bit RISC OS?
It's a case of supply, demand and competition. There was a demand, ROL failed to supply (over the course of several years) and so Castle stepped in. It has to be said, ROL did have years to do this. It's not as though Castle bought RISC OS a year after Acorn disappeared or anything.
With the hardware and the OS with the same company, there is a more sure future for the platform.