Interpersonal, HR related issues are usually very low on the list of things your manager enjoys. Assuming you're well known for publicly discussing salary, giving you an average raise and keeping you at the same salary might make you a little upset when you feel you deserve more (to which you might get a "my hands are tied" or "there wasn't room in the budget, this time"), but giving you a salary that eclipses your colleagues will make the rest of the team angry -- and probably a lot more angry than you'll get by just receiving the average. Unfortunately, the math ends up being not to your benefit.

Smart people make more money, then save it and then use the fact that they have 6 months expenses saved to leverage getting even more money.