Poe was supposed to die like 20 minutes into the film. His surviving was a very late decision.
Yeah "a late decision" and unfortunately his character kind of reads that way.
He could have used something more, one scene of exposition that gives him a character arc.
Way back it was suggested he was the only "true" survivor of Alderaan(native not adopted). last survivor of his line.
This simple reference would have added incredible weight to his character.
During the torture scene Kylo could have plucked this otherwise meaningless "fact" from his mind, used it against him as far as -
where is the map -why are you protecting the Rebels -
you know it's because of Leia(not a true Alderaanian)
who led them to Alderaan that all your people are dead. ...they brought this upon you...? etc...
This could have been used against him, and helped define character and purpose.
That way when he cracked, it gives some personal weight, doubt, humanity, to who he is, what's at stake for him personally, because deep down there is actually some truth (from a certain point of view) to what Kylo exposes.
So how would he react?
When he then disappears in the desert during the first act, you might question why he took off, like damn, Kylo really got into his head and 'efd with his reality and "truth".
Maybe he has abandoned the Rebels and their mission, that's why he's gone.
This would have carried over to when he does return, with an epic fleet of Rebel X-Wings behind him.
And with little exposition, giving him a much stronger a character story arc, like ef-yeah! They couldn't break him! Giving it a more personal struggle, and weight.
When you do see him and Leia together, you know what it means to them that he wasn't broken, that he recognizes her as their leader and why he always fights by their side.
