But does that really feel like Barkskin? That's my secondary complaint about the spell (the first being the odd drafting). It doesn't make sense that a character with tough skin wouldn't benefit from a shield or from ducking behind a wall. Intuitively, tough skin and cover should stack. (And doesn't a focus on naturalistic rules means that we should be able to trust our intuition?) Giving a base AC when you have nothing else going for you feels more like a luck or divination spell, not a transmutation.
...
See, this is the biggest problem with would-be rules lawyers interpreting guidelines. Some folks think that asserting "rules as written" is ample justification for the most counter-intuitive and frankly ridiculous readings. I mean, seriously...
barkskin doesn't stack with cover? That's completely preposterous.
The description of
barkskin isn't particularly vague, if you just read the plain language of the spell instead of trying to parse out something that's too clever by half. The spell is named
Bark Skin. Its description begins by saying your skin becomes bark-like. The spell is very obviously designed to provide protection. This is, clearly, a spell that gives you natural armor. Natural armor doesn't stack with regular armor, and the language of the spell is a little awkward because it also isn't intended to stack with other natural armor for a target shapeshifted into a durable beast.
Now, I'll freely admit that the spell is not well written. First, the language is unclear about whether the base AC 16 natural armor is intended benefit from dexterity. Secondly, this is (like the equally questionable
stoneskin) a spell which is clearly intended to provide defense in combat for one or more encounters which nevertheless requires concentration. Still, to interpret the spell and the natural armor it clearly provides as somehow not stacking with the protection of a shield or cover is some seriously tortured logic.
Personally, I blame Crawford for this phenomenon. He's been very supportive of this idea of the rules "as written" being distinct from (and, bewilderingly, superior to) their intent, and has even gone so far as to adopt a few questionable interpretations as "official," at least as much as anything published only on social media can be considered official.