Yes. It's entirely your fault, Kikatsu. Have at you! *stab*
Anyhow, there's no reason Fission and Fusion can't exist separately for different applications and cost ranges. Taking into account the thriving plutonium industry and nuclear devices commodity, higher-efficiency fission type reactors might have applications that fusion powerplants would be too expensive, dangerous, or maintenance intensive for.
Considering that a fusion plant means having a self-contained miniature multi-million degree sun on your ship, any breach of containment would cause very bad things to happen, plus, it requires humongous magnets to keep the reactor from becoming screwy, which could interfere with computers or sensors or something. A fission type fuel pile could theoretically be more controllable, cheaper, or simpler to operate. The only real moving parts it would have, at it's barest, are control rods and coolant pumps. It can still melt down if coolant isn't applied or spew radiation, but that's a bit better than 'spinning exploding ball of plasma in the middle of ship'.
