You’ve spouted a lot of fallacy here, indicating a projection of values; assuming your personal opinions and experience regarding customization are objective, and reflective of other’s experience, when they’re not even remotely accurate for many players. The evidence is all around you.
Something which is jawdropping to me though is: do you honestly think if players had more freedom to customize and get invested in their character’s appearence, the game would be worse off and “die within a month”? What is the logic to that? Can you honestly not see that players will care more to play longer and buy weapon skins etc if they’re engaged with a progression system built around “being their own spartan”? The devs realized this was important- and they have since Halo 3. Why do you think you know better than everyone else including the developers of Halo games?
If you’re not getting your perception of these things from the evidence around you: the stated opinions of the player base, alternative (and successful) monetization models: then what ARE you getting this perception from?