Because of that, I think that this places quite a bit of bias in the game systems we tend to play as a group. Whereas I think my preferences now tend toward the rules-lighter, less "crunchy" systems like Hollow Earth Expedition's Ubiquity, there is by definition quite a bit less player investment in character mechanical development as compared to a d20 system on the opposite end of the spectrum. In the latter, a character is quite defined by the mechanical bits that comprise him, and these can be planned out in a multitude of combinations throughout the "growth" of the character's life. A player can (and my players do!) plan out which classes, feats, skills, talents, and equipment he will take at each level, as well as which prestige class he will qualify for and train in. In doing so, the mechanics define and shape the character just as much as - or even moreso, the original character concept. And that large investment of a player's time into planning out the character translates directly into the player's investment into his character.
I wrote yesterday that I'm thoroughly enjoying the Star Wars Dawn of Defiance game that I'm currently running. And while I don't think that the d20 system is a good representation of the Star Wars universe (especially when compared to just Episodes IV - VI), I think each player's investment of many hours into planning how his character is going to developed has helped to continue driving the game onward - they want to play their characters just as much as they want to see their characters reach their goals of getting this prestige class or that feat combo. I'm not saying that this is a bad thing - in fact, I think its great that this aspect of character building really draws the players into knowing their characters VERY well (no, "wait, what's my bonus to hit now?") and gives them an attachment to the character such that a PC death does cause waves; its just, I would love for a system that combines this aspect with a more rules-light approach.
As an aside, one system that I think manages to balance well the rules-light flow along with a great flexibility of player options and foreplanning is Savage Worlds (and to a lesser degree, Warhammer 40K RPG). There's enough planning possible for the gamers who like the crunch, but still a very flexible and rules-light deployment of the mechanics. I think Savage Worlds would make an EXCELLENT vehicle for running a Star Wars campaign.