I think borderlands could really do with some long term effects of battle and your own finesse.
For example say that you can gain 10% more shield strength, shown in a slightly different colour on the shield bar. The way you gain it is it gives you a point after each battle, if you aren't too badly damaged in it. The more damage you take, the less likely you'll get the point. Once you have, say, 10 points, it gives you the 10%. You can collect up to say around 30 points in storage. Because if you take heavy damage you'll lose the extra 10% shields.
This means even a battle against just one guy matters, because it gets you points that keep you tougher. You'll treat that battle as important, even though it's just one guy, rather than just sort of kludging through it because he'll never kill you and so what.