Fusion is so useful though. It is easy to set up on ships because it requires no consumables other than the fuel cells, and it has a small footprint. It is easy to set up power on all planets by stamping down a blueprint, and requires minimal resources shipped to them. If you're not expanding the factory, you probably already have a setup that works, so I can see why it would feel useless. But, when you want to double, or 10x your power consumption, fusion makes it easy.