Morale bonuses *shouldn't* be stacking but w/e. No one has shield AC generally since shields are for chumps so it's fine. Shield is +4 at level 1, not sure what you're on about. You only need like 3-4 of them to cover all the important people being attacked so not being AoE is fine too, you can handle it at low levels.
It stacks because they're rare. Can you name another? Does anyone even play the damn game? There is no bug.
Shields are not in fact for chumps either. Whether Shield-bashing (there are several very good ones starting in ch. 3) or just using it for the bonuses (and not just AC) you're underrating the value of item slots as much as the Armorless addicts. Even fighting one-handed is often enough since HP doesn't scale as hard as AC/Stats. I find it a more satisfying game by dialing down the damage, but even then stuff ends up dying in a round or two. There are no bulletsponges.
Shield spell is +4 for one minute at lvl 1, and it takes awhile until you've got enough slots to keep it up consistently. Yes of course it's great lvl 3-5 to keep your Leopard tank alive on Unfair. Shield item AC is always up, even when ambushed or dispelled. Tower +3 is on sale at lvl 6, and there are two +2 Mithril shields available by then as well. Throughout the game there are good Bucklers and Light Shields with other bonuses. Seelah comes with Shield Focus so is incentivized to use them, and there are other Shield Feats that unlocks in TTT/Dark Codex.
Find me shields that actually give useful bonuses that are worth more than higher damage dice, 2h bonus from mythic power attack and reach.
In fact, the shield bonus for a tank is much rarer than morale. Pets can't use a shield, it's +4ac for free.
If you use TabletopTweaks it means that if you don't have a free second hand you can't use crane style lines.
Don't even mention tower shield. Using them if you're not a tower shield specialist (which is probably the worst subclass for a fighter) is self-impairing.
As for the morale bonus, it's a bit of it.
The most important items are definitely:
1) Helmet of Comradery (up to +3) (act 3)
2) Lizard's Tail (+3) (act 4)
3) Ring of Triumphant Advance (2x morale bonus) (act 4)
Lizard's Tail only works on pets or characters with a polymorph effect, any effect of this type will work, so the animal aspect will also work (another reason why the alchemist is better).
You can argue that both belt and ring are available quite late, but you can get the helmet very quickly (at the very beginning of act 3).
AC stacking isn't terribly necessary in act 1, and for most of act 2, you don't see enemies that can reliably hit a well-built tank.
Neither Lann nor Wend need to be respecced for anything but variety.
Wend doesn't need a Mount because she's a great tank. If you've never tanked with Legendary Proportioned Wend Dual-Wielding Throwing Axes with Greater Snap Shot, Fighter's Tactics, and Seize the Moment you're missing out.
Again, Mounts are for characters who get a benefit from them. Neither Lann hitting from 50ft* nor Wend with high AC and Armor Training need that. Maintaining high DEX and STR on a Fighter is a non-issue.
* - Advanced mode on Lann would be using Abundant Step to take advantage of his Combat Reflexes but I have yet to reach that level. He has fine AC too by then with WIS to AC and Monk AC bonuses.
I wonder how this is possible for a normal fighter. Of course, I assume that this is not some level of difficulty for children like normal or daring
Theoretically, it could be done with a mutation warrior, but a regular fighter has no right to be able to tank effectively for the first 3 acts (last stand doesn't count).
Even assuming you are playing with TabletopTweaks which adds new mythic powers you still need at least some mythic lvl.