It seems rather fair to say that this thread is less of an debate at this point and more like a team battle of "not all Stages are fair for all characters" and "Randomness should be eliminated from the game" Vs "Suck it up and deal with it" and "Its how its meant to be played"
Frankly, Sakurai didn't Specifically make Brawl for the pros, and they didn't specifically make brawl for the Casual players.
It would be more fair to say that it was made specifically to please both.
odd and random stages thrown in so that, when a bunch of friends are sitting around a TV in their living room playing a rousing game of Brawl, and Halberd's claw comes out of nowhere and snaps someone to their death, everyone can get a good laugh and go on about their game. i know when i first encountered it i laughed my socks off, and i have no qualms with playing hazardous stages every so often among friends.
But on the other hand, they added the ability to turn stages off of random so that when theres a room full of pros, with the smell of competition in the air and money on the line, no one has to endure narrowly dodging a cannonball, getting overwhelmed by a lava wave just because their opponent was already by the safety tube, or trying to get back when the stage randomly flips every-which way.
It is, for all intents and purposes, the exact same reasoning behind items being banned.
In a competitive situation your job is to fight the enemy, not the stage, and sure, lets pretend we have a stage that offers Marth and advantage over Kirby and the Kirby still wins. Good job Kirby, you are a real trooper for taking the beating in a dis-advantageous stage and coming out on top. Now lets pretend the Kirby lost in that stage, but was more than skilled enough to claim the day on Battlefield or someplace of the like, fact remains that no matter what random occurrence gave Marth the win, he won when the Kirby should have if put on fair ground.
Obviously, something as obscure as personal preference in stages must be overlooked, a stage will not be banned merely because you don't like the slight shift in platform positions compared to this other stage (unless of course you decide to, as was suggested countless times before, Hold your own tournament), but when it comes down to hazards and random events causing ludicrous and unpredictable deaths at no fault of your own, they show nothing but luck, which has no business in a competitive situation.