First off, armor is awesome. Looks good, keeps you in the fight, and keeps that medieval theme going. A lot of newer fighters really want armor for an extra hit where they get hit most often. This actually has the potential to be detrimental to their development, as they are relying on armor to compensate for missing technique or a flawed guard. Learning how not to get hit there is of far greater value. This is a problem I see more often with first or second year fighters.
By time a fighter has reached a certain level of skill, armor becomes a safety net. It becomes that extra hit needed to overcome a hard fight or multiple opponents. Armor at this point also serves to reduce the impact of backstabbing and support weapons on an otherwise decent line fight. A fairly large chunk of the sport uses armor in this fashion, as passive defense.
Ideally, if you've developed a talent for fighting, you can defend yourself well enough to not rely on armor for survivability. Footwork keeps those greaves from getting hit. Good blocking and safe swings keep your arm armor intact. Shield work and every thing else combines to save your torso armor.
So, you've got all this armor and enough skill to stay alive fairly well, but what purpose is the armor serving now? It becomes a tool, a weapon to use, rather than passive defense. Those well practiced in armored combat will actually sacrifice hits on their armor to gain an advantage. Several high risk attacks now become more advantageous, with the knowledge that your armor will take the hit.
This is a bit of a slippery slope, however. It isn't worth throwing a risky shot when a safe one would have done the job. It also could build bad habits when fighting without armor. Intentionally allowing your armor to be hit should only really be used to gain an advantage that is otherwise difficult to gain.
One of my favorite tricks to use armor offensively is against a legged opponent. Raising my greave to block their angle of attack and force a hit to the armored leg allows me a chance to hit their exposed arm. That's a pretty fair trade. Doing the same without armor takes a little bit of good timing, but armor lets you get away with an aggressive attack and end the fight relatively unscathed.
That's just one of many examples (can't give away all of my tricks). The point is, don't look at armor as a "just in case" or a necessity for survival, think about how you can use it as another part of your arsenal, just like a sword or shield.
Also, make/wear more armor. It makes the sport look better.