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So; if Legion becomes popular, there will be more and more expansions, with probably another power creep, which means that several years in, players might have a similar new edition forced upon them, with all the associated costs.
X-Wing has a very popular competitive environment and those updates are aimed at that scene. I'd be surprised if a mass combat game got to the point where it required the sort of updates and modification that X-Wing is going through
Also, it's Star Wars, so you can make blaster and lightsaber noises all the time. What more could anyone ask for?