I don't disagree on some points, but I'm not sure it would fly.
The negatives:
People who are interested in getting something as nice as a 3805 and a 3910 don't generally mind poring over equipment stats to decide on the right equipment, and are comfortable with interconnects. It would weigh a lot; more than my glass-shelved Bell'O is rated for. Some people, despite the cost savings, might want more or less receiver, or more or less disc player. Or, they think Denon makes the best players, but would only mate them with an Onkyo, Anthem, H/K or outlaw amps...i.e., they wouldn't buy those two components as their first choice. Finally, if something went wrong with one section or board, they might likely face having to replace the whole thing.
The positives:
Easy setup, would look cool, theoretically, the in-chassis transfer from disc to amp cuts down on some circuitry, and finally, the savings on two chassis, two power supplies, and duplicated D/A converters would save money.
The issue for the manufacturer is: Is the product such a likely success that they will get a return on the marketing, engineering, advertising and distribution of a product... and they're likely to go with what they really believe will be a winning product. Separates are proven, a combo unit as you described would be very cool to some, but maybe not enough to make the product a virtually-guaranteed success.
Personally, I'd like it and would have bought it considering they are the two components that I wanted anyway! I'm just not sure there's enough of us!
