It's not as modular as you might think. some stuff depends on other stuff being there.
Perhaps - but the stuff with dependencies build upon the obvious requirements. Just want the redpower wires? Get wiring? Lights are nice, obviously they need wires. World only relies on core - but of rcourse you're going to want to do something with the stuff - so Machines depends on it.
Whether you admit it or not, you can pick only the modules needed for what you want to do.
If BC/IC/RP were collapsed into one and everyone followed the same API and had the same path do you know how epic that would be. It would basically make the game that most of us want to be playing already. You know the one that takes energy management/resource management with a dash of hardcore automation and makes it fun. instead Elo is just going off to do whatever she wants and doesn't seem terribly concerned with who she steps on.
I think FC's departure from the Forge team shows what happens when you rely on a bunch of different people to try and make the One Mod To Rule Them All... It's good that she ironed things out with Alblaka and that SpaceToad is still on board... but what if they decided to go their own ways? Where does that leave her? In the end, she's got to be able to make the mod she has in mind without counting on someone else's mod. What woulld have happened if she built much of her mod on things from Better Than Wolves? Now that FC has guaranteed incompatibility, RedPower players would be the ones who suffer for his choice, not hers.
As it currently stands, RP works well with IC and BC (I nfact, even Eloraam plays with all three in her worlds). Yes, there is some overlap - that allows people the choice of what they want to use and how they want to do it. If ANY of these three mods required one or both of the other mods to operate, then that developer would be at the mercy of the other developers' whims. Those of us who like using all three have many options - those using one or two still have some option to do whatever they're looking for. You'd have a hard time convincing anyone that this is a bad thing.
See, you already CAN play that game that you want - you don't need to roll all the mods into one (as nuce as that might seem to us). Just use what's there and realize that the mountain you stand on is in fact a molehill.