Pardon my ignorance: why is the 7M-GE so much less efficient?

[finaltable]

Even if you were comparing one Toyota to another there are a lot of things not being taken into account here. Compression, volumetric efficiency, internal resistance and friction, interia and the weight of the stock internals, the RPM at which the power is made, the tradeoff between torque and HP, bore, stroke, valve timing, factory tuning, and so on.

I like this response better than being told I am just clueless. I started out by saying I don't know the answer to this, silly me for thinking that a forum frequented by people knowledgable about this car/engine (and engines in general) might be able to help me understand what makes this engine of 20 years ago different from the engines being made today. I thought comparing the BMW engine to the 7M was actually a good comparison since it makes sense that 20 years later the 3.0L straight 6 (a good design to start with) could be improved by about 10-12% in HP given a similar performance target.