Hehe yamahuh you're a dork.
Yeah swimming is INCREDIBLE cardio work and is low impact so you're joints take very little abuse. And while swimming could be an awesome addition to a any type of fitness routine (bodybuilding included) I think the main reason it isn't used as much is it takes a lot more time to go shower, change clothes, get in teh pool, shower, change clothes than it does to walk over to the tread mill.....walk.. done. Lean mass also sinks, add that to the limited range of motion advanced musculature causes and swimming becomes more of an inconvenience.
And lets face it.. anything that is difficult will be avoided.
From 4-9th grade I was on the swim team and let me tell you that is HARD a lot harder than track or soccer you throw up a lot more.
balance really is an awesome and yes VERY overlooked aspect. I started training as a freestyle skiing coach and we did all sorts of wacky balance drills. We had one guy that could jump up onto swiss ball with 95lbs on his back and squat while standing on the ball. not a regular drill because of the risk but impressive.
I have to disagree though on weight training not improving balance and coordination. WEight training with machines may do very little for balance but with hundreds of pounds on your back your entire body is working very hard, and very very rapidly making small adjustments to keep that weight from getting out of hand. it only looks slow and cumbersome. Squatting or any press over the head and the core of the body is working nonstop to balance the weight. if you are simply doing a dumbell bench press your arms are doing a pretty amazing feat of balance. you get 50,100,200lb dumbells on the end of an outstretched arm thats a very top heavy situation just to keep it up you are constantly making adjustments. And then lowering it and raising it you are constantly altering your balance to keep that weight from getting out of control.
I guarantee you anyone that can balance a few hundred lbs on their back squat down then stand up again is going to surprise the pants off of you in a balance contest.