The fixation on the aesthetics of Fallout has led to its stagnation.

It's one of those things capitalism ruins. For Fallout to work as a brand, there needs to be brand recognition

It's why they still use caps after it stopped making sense and why you see Power Armor, Vault Boys, and the Brotherhood of Steel everywhere. It's not Fallout without those aesthetics, so everything associated with those aesthetics will stay past any logical reason.

It's kinda sad really, if you think about the implications - since the aesthetics are tied up in Americana, it's going to be a lot harder to tell stories from perspectives other than those affected by American companies. That's cutting off worldbuilding for several countries they played a big part in the past. They won't sell without brand recognition.

So the world becomes smaller and less real. Nobody will break away from eating Sugarbombs or drinking Nuka Cola. Hairstyles and fashion will either reference the 50s or just have vague Mad Max vibes. You'll never spend the majority of your time outside of the US wasteland.

The world becomes less hopeful too. By virtue of the franchise's premise, clear in the title, the world will only ever be ravaged by nuclear fallout. Any happy ending you get in any of the games become divorced from one another to maintain the status quo. That or a retcon or later event ruins whatever changes meaningfully in the setting. The world will never heal because Fallout needs a broken world.

It sucks because Fallout still has great potential for political commentary and satire, but it's confined in its messaging because because it's owned by and they don't want to criticize shallow consumption if their profit relies on shallow consumption.