This is interesting.
It kind of addresses / supports the conclusion I came to regarding a situation I had my last session. Which is related to focus in a role-playing session when dealing with wilderness travel.
In my game, the group was trying to clear out an orc lair to prevent them from raiding nearby settlements. They had a vague idea of where the lair was (30 miles to the North East) but that's about it. I didn't want to hand waive the travel with narrative: "you travel 5 days and are at the dungeon", but the players didn't really want to spend all session going hex to hex until they find the lair.
I want to have a mechanical answer for: "We want to stop the orc raids by clearing the orc lair to the North"... where the exact location of the orc lair is not known.
It depends primarily on the focus of the session and I think both methods are useful. If the players' primary focus on the session is "find the orcs and clear out the lair", then you'd want to abstract the travel (the Navigation check in these rules represents an abstraction of finding orc tracks or finding disruptions in foliage suggesting passage of an orc raiding party, etc). If the primary focus is instead "We want to explore the wilds and look for the orc lair" then you'd want to use the hex crawl method (exploration is the desired focus, let them travel in detail and find what they find).
You could even switch between the two... the UA Into the Wilds abstract rules can get the party to find the Valley of the Ancients, but then a thorough hex crawl can be done when actually exploring it.
I think this UA article can stand to be expanded on, but its a good start. What I would like to see (some already mentioned):
1. Weather - more detail on how weather can effect things.. you can apply disadvantage to the Navigation DC, but I'd like to see something more mechanical (Maybe an abstract weather rating - clear, inclement, severe; combined with heat, cold, rain, snow that can affect movement and rest).
2. Chance to stumble across something along the way... not a wandering monster, but a random feature or thing (ruined structures, natural shelters, magical pools, stone formations that have divination or teleportation magic, etc... there should be a chart of things of this nature for each region). Sometimes, this is just wilderness dressing, other times it may actually be a dungeon or lair or something that may actually sidetrack a group.
3. Wandering monster chance should be decoupled from random feature chance. There should be a chance of coming across a magical pool (rolled for in 2.) that, from which, harpies are drinking.
5. I really want D&D 5E to bring back "% chance in Lair" with lair rules for various monsters (i.e. a randomizer / procedure for number and disposition of orcs in a typical lair).