White Wolf used to do that with all their games. The thing is, if they're meant to be standalone games, they need to do that!
I liked the WoD approach better: They put all their common rules in a 'World of Darkness' core book, then released one specific core book for each of the different 'species' populating WoD, that described how they differed from the default. There was some overlap and duplication, but not as much as in FFG's Star Wars core books.
Anyway, it's okay provided the rules remain exactly the same each time, or if the rules changes are very significant. That way, you either don't have to worry about it or the change is so large it slaps you in the face and can't really be annoyed. Just as long as they don't make small changes that require you to carefully reread the whole thing to pick up on the minutae...
[...]
Oh. Never mind then.
I haven't noticed any actual rule changes. It's mostly just added (or different) 'fluff', examples and clarifications. In AoR, there's one additional skill, several new pieces of equipment and different ships. That's about it.
Regarding previous Star Wars RPGs, I only know the version from West End Games. My memory about it is very fuzzy, though - too long ago that I played it. I just remember I didn't like it enough to play more than a few sessions.
Judging from what I've read so far, the FFG version has a few skills too many for my taste, but I really like the system of careers and specializations. In particular, I think it's great, that there's no limitations regarding how many specializations you can take, and that you aren't limited to choices within your career. Since it doesn't use levels (you just expend xp to buy specializations, skill ranks or talents), you can really pick and choose to create exactly the kind of character you want to play.
Oh, and I can't wait to get my hands on 'Force And Destiny', duplicated rule text or no!