Porsche did put a V8 in their 928 though. I would rather have a V8 because they run smoother. The torque comes on a lot smoother in a V8 and they just sound a whole lot better than any other engine. V10's sound terrible.
The main reason I would want a heavier less powerful engine is because its a lot easier to modify, and cheaper to build/buy a simple large engine than it is to modify a high tech small engine. Its an American philosophy but I would like to apply it to a BMW where you get great handling and braking, etc too. I'm glad to hear the current gen is getting a V8.