I too have come to the conclusion that the way fame works lead to a universalist approach that makes the games feel a bit samey. There should be more tiers of each approach so you can truly go at it as a builder or an expansionist or an agrarian, or a militarist.
I don't think it's the fame system necessarily that does this. In fact, I think pretty much every 4x game has the problem of things becoming to samey at the end, with the possible exception of Endless Legend since that has vastly unique civilizations to pick and through the missions system every civilization/culture has a basically unique win condition.
But Endless Space and Civilization definitely also has the issue of things becoming too samey in the same way that Humankind does. In the end anybody going for a science/economy/wonder/supremacy/diplomacy victory will also need to be universally strong to keep up and actually achieve those things. In fact, I think Humankind might have the edge on Civ IMO because at least in Humankind with the changing civs, you will have unique units/districts each era instead of Civ were every culture is only really unique for one or two ages.
And I don't think the star system is really that restrictive or forces a player into a general playing style. For example, in my last game (mentioned in my earlier post), I never once fought a war (or really fought anyone, except a few independents here and there), hardly expanded before the medieval era (when I could reach the New World via the Norse culture) and focused mainly on earning a lot of money and still ended up in first place while being very specialized. And I do really like the way the fame system works. It makes every part of the game count instead of just the end, since a player that did extraordinarily well in an earlier age and slowed down a bit in the later ages can still reasonably win.
I think the main issue I have with the way the endgame plays out is that the way resources are distributed makes it hard to really go for anything except for the ending where the max turns are reached or where you research everything (or destroy the earth via pollution, which is a bit of a half-assed mechanic in itself). But the other two are much too difficult to achieve right now because you might just randomly get fucked out of resources.
Like, in my last game I wanted to go for the Mars mission victory, but to actually finish the second stage of that route you need two oil. Now, I had one oil due to a trade with the one AI that raced to the Contemporary Age, but the one other oil on the map belonged to another civ that was still two eras behind so he had no way to actually exploit the oil and trade it to me. And sure, I could've broken the alliance, got my war support up and attacked him (something something Gulf War), but I didn't want to because I was playing a pacifist game. So that ending condition immediately became impossible, because there was no way that that civ would reach the age in which he could exploit the oil before the game ended.
Military victories have a similar issue, with the final tier units needing so many resources that it's basically impossible to build them unless you get very lucky with the resource generation or have already pretty much conquered most of the map. Like, the helicopter gunship needs 2 oil and 3 aluminium. How the hell are you supposed to get that when the average map spawns maybe two oil in total. At least this follows the rule that if you can't build it, the AI probably also can't, but it ain't great.