Seems like a lot of resources devoted to the fighter's AC.
It is - actually, it's a bit too many, but his AC doesn't drop so much if I take some out. It might drop to being hit on a 17!
The trouble with defending against spells, touch and special manoeuvres is that (in general) there isn't any defense against them save spells that counter their effect. A purple worm has a +36 grapple check - I'm yet to see any sort of PC who can defend against that without (a) being a monk focused on defense or (b) having freedom of movement. Likewise, you might have one or two good saves, but all three? At the levels a properly optimized foe will cast against you? There's a huge disparity between the DCs of spells at higher levels and the low saving throws of characters.
There's a foe in the final book of Kingmaker who casts
mass hold person with a DC of 23. You probably should be 17th level by that stage, which means that a fighter with a +5 cloak and a 10 Wisdom has a Will save of +10. What's the counter for that? Really, it's a
ring of freedom of movement. In that campaign, we had every craft feat between the casters in the party. (I don't think they made that ring, though - an oversight!)
AC works against most of the foes you'll likely face. And - for a relatively traditional campaign with more bruisers than special effects foes - it's really very good. Both my Council of Thieves and Kingmaker campaigns have had a PC who has focused on AC, and it hasn't proved to be a poor choice - and they've had good enough weapons to be effective.
Mind you, the purely offence-focused fighter is a scary sight. In Way of the Wicked, the 3rd level great-axe wielding fighter is attacking at +10 vs AC and dealing 1d12+13/x3 damage or thereabouts. (I think his AC is around 20). The disparity between his damage and that of everyone else is notable.
My experience is that there are a lot of items to boost AC, and not that many for attacks.
Cheers!