I continue to be annoyed by references to a single "D&D Multiverse" with canonically established cosmology. One of D&D's greatest strengths is that it can support an infinite variety of settings, yet the developers seem intent on pushing as many players as possible into the same one.
Regarding exhaustion, I think this is an illustration of the silliness of evaluating a choice between two options using an approval rating for only one of them. I also think exhaustion is a mechanic that merits more experimentation. In principle, I like the unique effects of the 2014 version more than the across the board numerical penalty of the UA version, but in practice, disadvantage on all ability checks makes the first level too harsh in the sort of exploration challenges where I most often want to use the mechanic.