Agreed. However, they'd never recoup the R&D costs. This is the only Defender with the AJ engine, unlike prior RR/RRS options that were designed with that V6/V8 option in mind. Personally, I'm super bummed about it too. I'd happily pay just for the motor as well.
Wat? That basic engine architecture is ancient, almost as old as the Audi 4.2 V8 block. Those development costs are long paid for. The emissions and transmission pairing is probably more like tuning the computers for the Defender (hence the numerous Nurburgring runs it had) rather than real design work....
This is a pure high-margin halo vehicle that they'll produce and sell in low quantities, clearly an AMG G53 competitor that will appeal to a similar clientele. They didn't have to redesign the engine bay as a MHEV inline six is longer and taller than a small block V8 with a blower in the valley, and they said up front in development that there would be a "halo Defender" offered so it was clearly planned.
More likely, they know that just offering the AJ V8 as a standalone engine choice, it would be too popular. With it and the SVR Rangies offered, they can't sell too many of them without a penalty on under-running the CAFE targets, which may even have some of those penalties baked into the cost just in case. Not talking gas guzzler tax, CAFE cap and trade penalties are different.