Too many assumptions though...
First, for YOU 2 subs are enough....for others is not. For some one is enough...we are all different.
Selective preamp on the 3800h is already high 90db SINAD so hardly anything between that and the 4700h in full preamp mode BUT , with the 3800, I could use my 7 channel amp and use the AVR for the atmos since I can do selective preamp. With the 4700h if I dont want to go down to 80db SINAD (at 1.6v), I will need an extra expense of a 4 channel amp.
Then there is also the feature of the tactile transducer which again, is a feature that some of us may use and others may not care about.
There is nothing "pipe dream" about DIRAC. It is coming March next year, pretty clear. Audyssey does A job already but is it as good as DIRAC? A lot of people feel otherwise.
It is not about paying more for uneded stuff.... it is about FEATURES that some people may want and others may not. So no, it is not about upselling, is about choices since we all have different needs.
In almost every ASR review category the Denon 3800 measures considerably worse than the Denon 3700/4700. It's a fact. Linearity degraded, Preamp mode distortion sets in early -15dB, Peak performance 0.8V versus 1.4V on 4700, 3800 DAC a full 10dB lower SINAD rating than 3700/4700, 32 tone test is worse. At every turn, the Denon 3800 is a downgrade from 3700/4700 measurements. If you want to trade performance for things most people don't need then you should buy a Denon 3800. Let's be sure it's not an uninformed choice for buyers.