Ah then it's an amazing plot if the point was that it was redundant! Totally makes it worthwhile and not at all.. er.. redundant.
His swap from wanting to bail to save Rey to being committed to the cause is such a bizarre shift though and people just hand wave and claim that Canto Bight was what caused this and not as if he just randomly decides to change. His motivation to go to Canto Bight was to save Rey since she would be going back to the Raddus after returning from Ach-To, he continues to be motivated by this all the way up to crash land on Crait (unless you want to claim his "Rebel scum" line to Phasma as meaning something) and then he randomly swaps and is happy to kill himself for the cause.
The patronising use of "Look closer" as if someone who has lived a life of servitude to the First Order and DESERTED THEM when realising the terrors they were perpetrating in TFA wasn't aware of the cruelty in the universe is just bizarre.
The fact that the mission fails doesn't make the mission redundant. Do we scrap IW because they don't stop Thanos?
Throughout both movies he makes decisions to help the resistance but doesn't commit. That is because his biggest confidant is Rey who has a similar mindset. It is only when he starts seeing the struggle through Rose's eyes he starts to see why it is important. It is through Del Toro's character that he is given the carrot to continue being ambivalent. He makes his choice on the 1st Order ship and follows through on Crait. If Canto Bight worked better it would be much clearer but all the element are still there.