Some interesting ideas, even if we've seen them before.
For the players make all the rolls concept, I agree with the poster above who asked why change the mechanic? Why not just have a player roll the ogres +7 great club attack against a PC's AC? Why go to the trouble of changing the math? You'll always have to convert any published material.
The Vitality Points variant is interesting, but probably has a couple of flaws. Nothing that can't be fixed or worked around though. I personally wouldn't use it as presented, but I like the idea. Others mentioned using exhaustion levels as a way to reflect serious wounds; I like that idea. Glad this UA article got the discussion going.
The Alternate Alignment is probably the least useful to me, especially since 5E tends to lessen the importance of alignment at least as a mechanical aspect of the game. Honestly, I always hated how a paladin could almost never be lied to in prior editions, so I like that they've changed that up. If I was going to make any changes, I would probably just eliminate alignment altogether. I don't really see the need to change it up. For those that do, may I ask why? What's the advantage of having an alignment like "Sky", to use an example from above?
I think that the UA article was fine. Sure, a bit sparse compared to others, but I think variety is useful. Most folks who are complaining seem to be seasoned players/DMs....folks who seem to need published material the least. Sometimes an article like this may help people who are newer to the game and haven't seen 3 or more editions worth of these variant rules.