Certain Areas That Won't Change
Admittedly, I ride older bikes. But I don't have an issue with newer designs and would not have an issue going to a modern carbon frame if I felt the need to upgrade.
But there are a few areas where my retrogrouch rears its head. One main area is gearing.
I have never been able to get beyond 7 and 8 speed systems; although I might consider a 9 speed one day. For years I've ridden a 12/14, 13/15, or 14/16 first and second position cogs. Adding another cog has always been to add range on the low end; 6 speed 24t went to 7 speed 28t. My mountain bikes went from 7 speed 13-34 to 8 speed 13-40.
About 5 years ago I picked up a road bike for my wife that had 10 speed 105 with a triple. The first thing I did, before she even took one pedal stroke, was to strip off the 10 speed components and install 8 speed 12-34 cassette with a mtb rear derailleur and Claris shifters. It takes her everywhere she needs to go.
I'm sure there are others that have one area or another where the line is drawn.
John