My daily driver is a 94 Trekking/Touring/City bike from a small manufacturer in Germany (Fahrrad Manufaktur). It has a unique Sachs 3x7 shifter system with 7 speed derailleur and 3 speed internal hub. The predecessor of the SRAM Dual Drive. Perfect for stop and go in city driving. Plus it allows for a full chain guard keeping the pants clean. It has a very rigid Oria Hi-Tension steel frame and double wall Alesa rims for my heavy weight and the heavy panniers I am carrying. Modern Trekking bikes aren't really any better or designed much differently. Most of them still use steel frames. E.g. Surely Long Haul Trucker. The only two more modern features I miss on mine: Front dynamo hub and hydraulic rim brakes like Fahrrad Manufaktur and Utopia are using on their current Trekking bikes.
So long story short: I don't see the advantage of riding a new Trekking bike.