I think you covered it well here. I think the Vega cards are decent, but they're struggling to be competitive.
The current prices are disappointing.
The rumours that 3rd party cards are struggling to improve on the reference cards is also disappointing (who wants an AMD reference cooler? Plus the LC edition suggests better cooling should allow better performance).
The fact they were released 14 months after the cards they're currently competing with I think is the real problem. If they'd released at the current prices like 2 months before Nvidia's cards then people might not have been so critical of the prices (they'd still be expensive, but with no competition it'd be understandable).
Also the fact they've not released anything to compete with the 1080Ti/Titan for those just looking for the best performance. Those videos that went around for a while on the history of everything Nvidia has ever done wrong (although no mention of AMD doing the same) classed the 1080 GPU as a mid-range part, so AMD are still only competing with a mid-range part with their top of the line products.