"being overwhelmed with choice" is hardly ever a real problem. what would be actually overwhelming is many, many competing forks, as the codebase fails to accommodate the flexibility that people desire from the game. of course, some people would probably eventually fork it and add an actual API, as this is the sensible thing to do.
you are failing to understand that the very specific (and to be honest odd) way that you like to play video games is not the way that other people do necessarily. this is quite evident. you are wondering why people do things a certain way, but refusing to actually accept the answer. you seem to think that a game must be composed entirely of things that are meticulously and perfectly designed to interact with each other, that if it isn't perfect, it isn't worth playing. that's not really how many people enjoy video games.
you're also taking quite a pessimistic point of view of mods' ability to work together. it is incredibly realistic for two mods that are not written with each other in mind to work quite well with each other, especially if there are robust APIs that facilitate their interaction.
it is a fun and genuinely great thing to be able to arbitrarily combine mods and sets of features. in modded games (well, mostly just minecraft), I find myself changing the mods around between play sessions to create new gameplay situations and interactions. and it's just a useful pattern in general! modularity is not at all unique to games. monolithicity generally produces inflexible software.