I think it's about all these characters who are broken and lost in some ways coming together and overcoming all of that.
Yeah, I liked that show when it was called Flashman.
(Sorry, sorry, it was just too tempting.)
To be serious for a minute, Gokaiger's homaged Flashman pretty heavily from the show's beginnings. Several villains and story beats have really obvious counterparts in Flashman. I'm kinda convinced this is why Flashman and several other 80s shows won't get detailed homages, to be honest. Doing one would amount to Gokaiger showing the audience its playbook. Most writers are thieves, and the smart ones cover their tracks.
Now, the idea of reviving 80s-style Sentai writing for a modern show is actually super-cool. There's a lot of great stuff the old shows did that just fell by the wayside as the franchise evolved, and you could do great new stuff with it now. If you look at the actual nitty-gritty of what the show depicts, you only get the idea of sad, truamatized characters with Joe and Ahim (and much moreso the latter than the former).
Marvelous is occasionally upset, but then he tends to default to being unflappable in a way that constantly trivializes the idea of the character's conflict. Luka is pretty clearly over all of her old problems unless it's a focus episode, and Don is no more than abject comic relief.
I think you're arguing what the show is
going for, but not what it's
actually executing. The actual character writing in Gokaiger is not consistently about anything. Characters have distinct voices but their motivations are often vague and impersonal. I think this is the result of so much of the writing being done by journeymen instead of vets like Arakawa, Urasawa, and Inoue.
By the by, Inoue seriously wrote a better Captain Marvelous in the Jetman episode than has ever appeared in the show before or since. Inoue completely understood what that character was supposed to be about and brought it to life in a way that makes it clear just how flat and lifeless he is in lesser scripts.
I
felt for Marv then, I felt like I really knew where he was coming from, and I really cheered when he stood up to the psychotic monster of the week. For once, he really felt like a man struggling to be a hero. What I'm saying is that I want to live in the parallel universe where Inoue was head writer on Gokaiger, even if it means sitting through a story arc where Gai falls in a river, almost drowns, and then begins to go blind.