Remember BR is only leasing 4x 789 with no current plans to take more. It seems clear that they are going to use these 4 frames as interim replacement for A332. I believe they are only leasing the 4 frame because Boeing couldn't deliver any 787-10 earlier so they brokered this deal with GEACS to keep BR in the Boeing widebody camp.
The main regional fleet of the future ("regional" probably include 10 hour flights to Australia) will be 787-10 which on paper will give BR lower operating costs than A333 and up to 10% more seats.
The lack of PE is not that surprising in the context of regional flights. SQ is also not doing PE in their 787-10 instead opting for lie flat J. For flights under 4 hours, it's hard to monetize PE... it ends up being free upgrades for elites rather than revenue generating seats.