Shardstone
Hero
I agree with you completely on all of your assessments.Oh did people not want the Hexblade? Everyone I knew seemed very excited by it when it was released.
And it's true, a lot of their UA's for optional rules has fallen flat, but there is something to consider.
Optional rules are DM country. Only DM's are interested in them. Players want Feats and Sub (Classes).
70% of D&D 5e players aren't DM's.
As for the Hexblade, Mearls talked about how the Hexblade was the lowest percentage thing they published, just barely reaching 70 percent after everything was said and done.
On line, such as on Reddit, Facebook, and even here on Enworld, there was much chatter about how the Hexblade was broken, was a sloppy fix to the pact of the blade problem, and had very hard to grok lore. The lore changed by the time it was published, but only slightly, and other words the class was printed as before, which a lot of people were surprised by.
Personally, I have no problem with the Hexblade. The warlock PHB subclasses are all either very passive or very situational, with some stand outs like the Archfey's reaction misty step. So, having a subclass that was actually strong and flexed what a warlock could do is something I very much appreciate.