It's not the same model though. You are comparing the cheapest 2015 dGPU-based model and the higher-tier 2016 dGPU-based model (with better GPU, better CPU etc.). The base 2016 dGPU model was $2399 (albeit with a 256GB vs 512GB SSD).
One do has to point our that there were indeed some shenanigans going on in the lineup. Apple did shuffle things around, they introduced multiple GPU tiers, they have reduced the storage size (forcing you to buy the next tier if you want 512GB) and so on. So one can definitely argue that there was a hidden price increase. I am just not sure one can pin it exclusively onto the Touch Bar. There were a lot of changes that went into the 2016 models.
The base 2015 MBP 15 had the 2.2 Ghz CPU. The 2.5 Ghz model had the middle CPU. The high-end was 2.8 Ghz.
I'm typing on the 2015 2.5/AMD/512 model right now.