when you play minecraft you can run around for multiple hours without issue, but, forcing player to do specific task is not good game design, currently you can't advance tier by killing mobs or just building, you forced to mine diamonds at bedrock level...
miners are not fun, basically there is no fun in building ic2 specific stuff without something like assembly bench (especially if unstackable items involved), since most recipes take multiple boring steps to complete (and hurge amount of mouse clicks), probably i will compile addon that will allow to assemble ic2 items directly by consuming ingots without need to actually "craft" anything by hand. (like crafting coil will cost 2 copper and 1 iron directly, without converting copper into wires first)
some alternative ore\drop\something\low tier massfab\crystalizer tech\something that can be used to get some diamonds and other stuff without leaving your base will be good addition (but this belong more to addons than to vanilla).
iridium also notable sample of bad design, i looted 5 nether fortresses and got no sample, this boring and frustrating (especially if you dont want to cheat), i cannot be forced, soo i just abandoned entire iridium part of gameplay.
i checked few mmorpg's with donate system, IC2e very close to such games, artifical limits, that can be lifted for real money...
I don't see how Killing mobs or Building is anything different then Mining. IMO, Miners are much more fun then a Quarry or anything, and much easier. The Majority of the people who play MC play it for much longer then just a few hours, including me, so getting end game in less then an hour is just stupid.