A plot longer than in the two previous games would drag on horribly, I fear. In fact, in both games, I was beginning to be a little annoyed with looking for all those starmaps/jedi masters. A long game is good only if the plot is constantly evolving.
KotOR games have so far pretty much followed the formula of doing an "intro planet" to set up the plot, then have four or five planets that must be completed according to the same basic principle before you can move on to the endgame.
If you prolong the middle game by simply adding more planets/starmaps/masters for me to complete/find, then I'll probably be so bored with the lack of plot evolvement that I just might stop playing.
That hasn't happened so far, but I can't say that I didn't reach the point where I began thinking "get the hunt for the maps/masters over with already, so that I can see what happens next". Because I play to see the plot evolve. I do not play for the doubtful joy of killing the baddies, collecting new gear, or wading through the graphics - those are all just icing on the cake, and if you take away the cake itself, what's left will make you sick...