We have a 13 yr old DP and I can't identify much about newer Class A's that I would like to have and can't. A lot of the stuff you mention such as appliances, etc, are easily replaceable, for example, we now have a residential fridge and a pure sine wave inverter. Our MH has a pre-EPA diesel without any of the pollution controls imposed over the past ~10 yrs. We get a very real 8-8.5 mpg on average and the chassis handles just fine without any fancy add-ons or Comfort Drive technology.
The only "thing" I think we lack that would be nice to have is an energy management system that would make it possible to easily run both A/C's on a 30A hookup, but that doesn't happen very often since we try to avoid going places where it is hot and I'm pretty sure I could add an EMS if I really wanted to.
I think the construction of older "high end" coaches was as good or better than many of the ones being produced today. I helped some friends do some remodeling on a recent Monaco and was somewhat taken aback by interior walls that seemed to have been made out of Styrofoam!