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I don't know where people get this notion that you need to be Sufficient Advanced in order to achieve starflight. We already have some near-term options on the table, ranging from beamed propulsion to nuclear pulse propulsion. Both of these could get us to 5-10% of the speed of light, with a magsail for slowing down. To a species with a lifespan measured in millennia (which is entirely plausible), that might be sufficient, but they could always go faster, or use hibernation. A 200ly journey could be a minor thing for them, and their colonization wave could quickly reach Terra from the other side of the galaxy, a few million years at most.
Why is it that when people think "interstellar travel", they typically think "faster than light"?
Pragmatism. Space is vast and virtually has no end. It would take a long long time and while in the grand scheme of things you'd be correct, in the short order of things like exploration or war, time is of the essence. Unless of course the aliens were smug, but I would not expect a smug view from a militaristic society of beings. I could see it from some non-militaristic ones, but those aren't ones we'd need to worry about.
For example humans live quite a while, though we're not immortal. We live for decades when nature I guess takes it's course. However, it's quite expendable to journey like people do. If things didn't need be done faster, cars, flight, and other technologies that accommodate (including animal husbandry) wouldn't have been utilized they way they were.