What’s up with Barkskin in D&D?

Barkskin is a spell in Dungeons and Dragons 5th edition, which my Elf Nature cleric automatically gets, and every time I look up this spell I kind of scratch my head.  The current online text states:

You touch a willing creature. Until the spell ends, the target’s skin has a rough, bark-like appearance, and the target’s AC can’t be less than 16, regardless of what kind of armor it is wearing.

Normally, your character’s starting armor class (AC) is 10 + dexterity bonus + armor bonuses.  My current elf cleric has an AC of 17:

• Starting AC of 10
• Dexterity bonus of +2
• Armor bonus +2 with shield
• Armor bonus +3 with chain shirt

Now, if my cleric casts Barkskin on himself, what would happen?

The official D&D rules site, has a ruling to this question (link here):

Q: How does barkskin work with shields, cover, and other modifiers to AC?
A: Barkskin specifies that your AC can’t be lower than 16 while you are affected by the spell. This means you effectively ignore any modifiers to your AC—including your Dexterity modifier, your armor, a shield, and cover—unless your AC is higher than 16. For example, if your AC is normally 14, it’s 16 while barkskin is on you. If your AC is 15 and you have half cover, your AC is 17; barkskin isn’t relevant in this case, because your AC is now higher than 16.

The gist of this answer seems to be: if the recipient’s AC is lower than 16 (no matter how or why), it’s now 16.  Full stop.  If the recipient’s AC is 16 or higher, Barkskin basically does nothing.

So with my current setup, Barkskin isn’t very useful for my cleric.  Nature clerics are proficient in everything up to heavy armor, so I can easily equip myself with the necessary defense without relying on a spell slot every combat.  However, Barkskin might be useful in protecting other members of my party who aren’t so lucky.  Wizards, for example, can’t use armor at all (apart from edge-cases like Bracers of Defense), other less melee-oriented classes also make good targets for Barkskin.  But casting Barkskin on your primary melee character basically does nothing.

Barkskin seems like a good way to shore up party defenses, but not necessarily enhance them.