I don't know, mining makes perfect sense to me.
Actually, I would introduce also a weekly use of water, oxygen and food, plus consumption of whatever fuel for FC energy, plus need of spare materials for limpets, repairs, ammo, ship fuel, etc.
In other words, all those things that you assume are automatically restocked by "the system" in the bubble and that you can't get when you are isolated.
Things like food could be either bought in sufficient quantity or synthesized from components you can mine, same for other things.
Unfortunately mining is the only means in the game to obtain resources from the environment (fuel scoop excluded), so unless the gameplay is radically changed, I can't see any other way.