I am very sure that it’s just you being pessimistic

The Polaris GPU in the MBP is seriously limited by the memory bandwidth since Apple has clocked the RAM conservatively in order to limit power consumption. HBM2 is going to be a game changer here since it more than doubles the bandwidth. Add to it 20% (at least) architectural efficiency improvement and the fact that Vega runs more CUs... and you’ll get a very impressive little device for its size.
And I agree with you that many photoshop etc. users probably won’t see much difference but that’s because their software is not good at utilizing the GPU. Of course, the biggest difference will be in games, but buying a MBP solely for gaming is a bit.... excessive.