We know they had wanted Brosnan, but he couldn’t get out of his Remington Steele commitments. Dalton was very much second choice, and without him, Bond in those movies would have been a lot less empathic.
That's not actually quite right.
Pretty much all of the Moore movies were originally intended to be Dalton movies. The producers said they first approached Dalton in 1968, for
On Her Majesty's Secret Service (the Lazenby one), but Dalton doesn't remember them approaching him until what would have been
Live and Let Die in 1971. He thought he was too young for the role.
They were absolutely desperate for him to be Bond so kept approached re-approaching him over and over (good taste honestly!).
With
For Your Eyes Only they were so absolutely sure they were going to get him this time, that they literally wrote the movie with him in mind, and then had to re-write it when he refused once more and the increasingly geratric-seeming (although not actually that old) Moore was brought back in.
And he was in fact first choice for
The Living Daylights, not Brosnan. But Dalton said "You've got to wait six weeks for me to finish what I'm doing", and the producers said "Argh no" and cast Brosnan who could appear immediately. But the Remington Steele people then re-upped Brosnan's contract. So that was a movie written for Dalton and he was first choice.
Sources can be found in this Wikipedia article:
Timothy Dalton - Wikipedia