I hope and pray that the developers are looking at changing this small tidbit of the game because i think that the weapon makes the character and I think an assassin would use 2 sabers instead of a staff.
It's not going to happen for a number of reasons.
The first, and most obvious, is game balance: if everyone can dual wield or use superior weapons (DBLS, Autocannons, Sniper Rifles, etc.) and your loadout is only determined by whatever you feel like using, players would be gimping themselves by using the suboptimal loadout (for pretty much every class except for tank classes, the optimal loadout would be to dual wield since that deals the most damage; for tanks, the loadout would be a superior weapon and a shield). It wouldn't really create much variation in appearance; it would just homogenize appearance based on other attributes. You could say that the developers could, potentially, add commensurate benefits to all of the various weapon loadouts to balance them out, but, at that point, you're asking for a lot of work for a largely negligible benefit (it's a lot of work for a mediocre improvement in customizable play), especially since, if there are any flaws in the math, you'll end up just homogenizing a vast majority of players' appearances.
The second, and the biggest one, is animations: every ability in the entire game would need 3 animations for all of the saber-jockey's (single saber, DBLS, and dual sabers) and 4 for all of the Tech classes (blaster rifle, single pistol, dual pistols, sniper rifle, assault cannon). As it stands, most abilities only have 1 (because that's all they need) and, at most, have 2 (if it's a common ability of 2 different classes with different loadouts). There are only two ways to get around this: either you make a crapton of new animations (which is a lot of work) or you reuse a lot of animations (which is boring to look at). Considering the "payoff" isn't really all that massive (most players are fine picking the class with the weapon they want rather than getting upset that their class of choice has a predefined weapon), it's not a reasonable use of existing resources.
KotOR and SWTOR are not the same game. KotOR was a single player game, which meant that game balance wasn't really a major concern. SWTOR is *not* a single player game; players are directly competing with each other, in PvP by trying to kill one another and in PvE by eking out better numbers than one another. Game balance between all of the various options is something the developers *have* to think about and consider. It's also not a continually evolving game so, rather than trying to pack as many features in as possible at release to encourage replay and experimentation (which will drive initial sales more), the development team has to consider what the actual development and in-game costs are for anything they work on. The amount of effort required to make an aesthetically diverse, mechanically balanced way for all of the various loadouts to be usable by all classes is just too high to justify it.