"All our accounts are joint"
In that situation everything in those accounts automatically goes to the surviving spouse, regardless of what any will might say.
"Interestingly he doesn’t feel the need to protect share."
I would guess that this is likely because he could not imagine you with somebody else if he were to die first. He may not have also considered how he would feel as a widower and he is attracted to another woman.
Although you and your DH are clearly very close, what would happen if he were to pass away first and you then later became enamoured of a younger guy (let's call him a 'gigolo')?
While I'm sure that you would never neglect your own children, you might choose to leave a large amount of the estate to your young gigolo on your death.
Likewise, if you were to pass away first then your DH may remarry and leave a large part of the estate to his new wife (if only by failing to make a new will after remarrying).
Or alternatively, you, or your DH, might decide to leave everything to your local cat's home charity. These things do happen and there are court cases about it that, sometimes, go all the way to the Supreme Court.
I often think of a will in a similar light to insurance. 99% of the time we don't actually need the insurance, but we get insurance just for that 1% chance that something catastrophic might happen.
Think of leaving your share of the estate in trust as similar to an insurance policy. 99% chance nothing untoward will happen anyway, so it didn't make any difference.
But what about that 1%, or 0.1% chance?