'Fans' complain left, right, and even center about this. But if you look at Finn's story arc for what it is, is it really that bad?
In TFA he's a stormtrooper that decided not to kill everyone (later revealed to be the force's influence), and rescued Poe. He's terrified of the First Order, but finds courage in Rey to face his fears and face the First Order and Kylo Ren. He ultimately helped the resistance with a support role in revealing a weakness in Starkiller Base's structure. Even though he is in the supporting role, he is a key role nonetheless.
In TLJ he relapses due to getting brutally injured by Ren, but in Canto Bight he learns how far the effects of the war reach through the corruption in the casinos and how that supports child labour. He's tempted with the option to quit and just profit off of both sides and live an easier and more enjoyable life, as all he's known since childhood is the First Order. Walking out on the war would have been easy, but wrong since it's more than just two people blowing each other up. He then affirms that he's committed to the cause and even takes Phasma out. Unfortunately he wasn't fully committed to the cause because his motivations lay more around revenge on the First Order and less about helping people, and almost killed himself. Thankfully Rose saved him so he could fight another day. In TFA, he was at the bottom of the resistance, and in TLJ he's somewhere in the middle.
In TROS, he stumbles upon other stormtroopers who didn't have the courage to fight back the way he did, and was the courage to them that Rey was to him. After Leia died, Poe anointed him General, filling in the gaps after Leia's death, and he's now the top guy at the resistance, after having been a lowly stormtrooper. He inspired Jannah to take up arms and became his star assist throughout the battle, and is seen to take out loads of troopers. The extra hands from Jannah's crew were also vital, especially with the Orbaks instead of speeders. He then literally took out all of the final order higher ups WITH THEIR OWN WEAPONRY. Talk about poetic justice, since he was a stormtrooper, and throughout the trilogy, was the guy to take them down. Yes, when watching the films we mainly focus on how the force awakens in Rey, but the force also awakened him, and ultimately he used it to help take down the Final Order on Exegol.
It's also dope how as far as a space battle goes, Finn basically shot them at point blank range when he took down the command deck. He didn't use a crazy weapon, or get a lucky underdog shot. He started as an underdog in TFA, but ended as a badass in TROS. The fact that he did so much during that battle also makes Rose's rescue even better.
Poe anointing him general is character development on Poe, as Poe always liked being the hero. This is great synergy.
It parallels how the force awakened Rey and later Ben to face Palpatine together. This goes to show how powerful the force is. Literally just awakening the right people who did the rest on their own, and also being with them.
So from stormtrooper and sanitation engineer to resistance hero and general.
So what the f*** are people complaining about? If this is about him and Rey not sharing a romance, then clearly that is the only thing you care about. Finding courage through someone else isn't the same as potential romance blossoming.
