I sort of look at older higher end DP's, as being the same as older homes.
Older higher end DP's, typically came with higher quality chassis and running gear, and many times better components, and always with better quality solid wood 'craftsman' like cabinetry.
Older homes, if built properly, have solid foundations, and typically better quality wood framing and other attributes that make them, well 'classic' like homes.
So a top quality upper tier DP with a superior chassis, are like and older home with solid foundation and 'good bones'. I feel they are worthy of remodeling and upgrading - to want a current owner would like.
Engines and transmissions and other chassis components, can be refurbished when needed. (But on the engine, many of these in the years talked about, are true 1 million mile engines. Sure, they will need maintenance and supporting components replacement of parts along the way... But certainly a good engine properly taken care of, should get you into the 500K mile range before requiring major rebuilds. (Some exceptions, ISX comes to mind as needing more expensive preventative maintenance. But engines like the C-12, C-13, ISM, DD60's - are long running and powerful engines.)
So someone looking for a coach t use for 10-15 years ahead - might be better off in the long run buying a 'solid and well cared for' top tier coach from the era the OP mentioned. Finding one in the $50-125K range. Invest another $75-125K into going thru everything and updating and remodeling and painting and say Active Air - to what the specific owner wants. And for a range of $125-250K - would have a coach that should 'classically and safely and economically' give them a solid 10-15 years of future usage. Compare that to some of the say 5 years old upper tier coaches costing $300-400K... And well you're money ahead, and lower insurance, and in some states lower DMV fees, and lower Sales Taxes, etc., etc...
And their is nothing wrong with either choice, some people move from a home, vs remodeling a home - as they just don't want to be bothered with the effort, and or research and work required, in upgrading a current home. Others, do their own thing, or help the local economy and invest big money into major home renovations.
Same can be said for RV's too... No right or wrong, just choices. And the right of all of us to make our own decisions. (Heck, last time I did a update of our costs on our coaches upgrades, solar systems, batteries, cabinet modifications, etc. - we've added another ~$60K into our towards the bottom of the top tier quality coaches. (Sure, some would place an 04 Allure towards the upper side of the mid tier coaches - again, opinions vary
!).
And you know, we're at this very time doing some 'what if' planning. Put another $40-60K into our current coach, or sell it and move into a same relative era Magna/Affinity/Newmar/Foretravel - and put that kind of money into a higher tier coach... So I'm more into going for olde top quality, then newer... with IMO, somewhat lower quality construction top tier coaches for several hundred thousand more then we'd spend staying older...
Best to all, and good luck with your choices. And I do respect all views this
!
Smitty