PC praguepride:
Is there a game mechanics reason to be a Skywalker, or is this desire "just because" kinda thing.
Simply being a Skywalker doesn't provide any game mechanics, but if you take the Legacy Destiny for Skywalkers, you'll gain the ability to spend a Destiny Point to treat your next Use the Force check as a natural 20. Plo Koon's Legacy has the same thing, while those of the legacy of Wedge Antilles or Nien Nunb gets the ability to spend them for 20s on Pilot checks. The Solo legacy does this for Mechanics, and Organa has the same thing for Persuasion checks (as does the Fey'lya legacy). Of the legacies that don't let you boost skill checks with Destiny Points, there's Fett (lets you score critical hits on 19-20 for the rest of the encounter), Koth (gain the ability to not move down the condition track as the result of an attack for the rest of the encounter), or Ackbar (double any insight, morale or competence bonuses you grant others until the end of the encounter).
The drawback, as far as I can tell, is that unlike regular Destinies, there's no way to 'complete' one of these - if you fulfill an Education Destiny, for example, you get a +5 bonus to a single skill of your choosing (which stacks with Skill Focus), and other Destinies let you boost your ability scores. The Legacy Destinies doesn't have any of that, you just gain one extra way to spend a Destiny Point.
But for me, the desire to play a Skywalker is mostly a "how cool would that be!?" kind of thing. :D