Rusty, I have plenty of 60 year old modern designer furniture and even some cabinetry that is veneer over the not even good stuff particle board. It holds up just fine. New materials are much denser (40-60lbs per square inch) with better quality more moisture resistant glues that meet all CARB II standards. Furniture board isn't the cheesy 14lbs per square inch crap that the box stores sold in the 80's for underlayment.
And a lot of new ply isn't the good quality that even the bad quality ply in the 70's was. A lot of ply, especially in the crappy import cabinets, has much more formaldehyde in it than the furniture board. And internal voids and skips. Some of those cheepchinese ''plywood'' cabinets need to go straight to the toxic waste disposal dump.
Folks who have that innate ''solid wood'' prejudice are hard to reach with the facts of modern cabinetry construction, so I'm not expecting to change your mind. If you want to pay more for the same functionality, go ahead. That's what the marketing geniuses are counting on.
The overall quality of construction of the line, and especially the finishes on the doors that you will touch everyday is more important than box construction--- once you reach a certain price point.
Q