"[W]et means soaking wet afterwards, after a concert. It just happens. It's a theory, a tactile, real way for me to go throughout a gig, like an effort. To get that wet, sweaty, to exert that much, to push that much water out of my body, [it means] that I did a good job. It's all just about not holding back and not restraining oneself. I always say, Don't stand on the edge of the water if you can dive in."
So the singer doesn't want to be like the person he's singing to. He doesn't want to watch what other people do, he doesn't care what other people think about him. He also seems to be telling the person he's singing to that watching what other people do, caring about them that much, is ultimately what's holding them back, and if they stop doing that, they too can "get wet".
From an NYRock interview with Andrew:
"[W]et means soaking wet afterwards, after a concert. It just happens. It's a theory, a tactile, real way for me to go throughout a gig, like an effort. To get that wet, sweaty, to exert that much, to push that much water out of my body, [it means] that I did a good job. It's all just about not holding back and not restraining oneself. I always say, Don't stand on the edge of the water if you can dive in."
So the singer doesn't want to be like the person he's singing to. He doesn't want to watch what other people do, he doesn't care what other people think about him. He also seems to be telling the person he's singing to that watching what other people do, caring about them that much, is ultimately what's holding them back, and if they stop doing that, they too can "get wet".
That's what I take from it.