"The thing with items and stage hazards is that both are detrimental to what is the ultimate point of a tournament;
skill.
Items are randomized, and nobody can predict where an item will spawn or even what item
will spawn. Items can also unbalance a match by adding RNG into the fold; and randomness as a whole is bad for proving skill. If someone beat a high-level player just because a Bob-Omb
happened to spawn by them at the right time, then that matchup was entirely unfair for the high-level player, because it was a lucky break that made him lose, and not his opponent being legitimately skilled at the game. That is why items are banned; they're too randomized. Randomness is fine in casual play, but when there's money and the possibility of being the tournament's champion on the line, items are the antithesis of "fair play". Adaptation isn't the issue, it's the
luck factor. There's absolutely no point in playing as best you can if someone else could get the one item that would punish you for being good or an item that does insane damage and knockback, or an item that grants invincibility, or that lets them throw down a mine that you don't see, walk over and get KO'd for what walking on what you thought was safe ground. It's too much to consider, and the randomness of item spawning only makes it worse.
As for tiers, they aren't lists of how good characters
are; they're lists of how
well certain characters do in tournament play. Characters like Pichu are considered bottom tier because they are, by themselves,
incrediblydifficult to use effectively in high-level play, while someone like Fox is considered top of the class because they're used so often and have such good results. As an example of how tier lists can change; Mewtwo, when the Melee competetive scene was still young, was regarded as being in the F-Tier (basically, the bottom of the barrel). As more people started using Mewtwo effectively, up he went in the list before settling in C-Tier.
And tournaments
are fun, just not the casual "Oh, let's pop this game in and just mess around" type of fun. Watching or playing in a tournament is like watching or playing a sports game; either side has fun, but in slightly different ways. Let's face the absolute truth here; without tournament Smash play, we'd have never had the Super Smash Bros. Invitational, we'd never have had the Gamecube Adapter for the WiiU...loads of things that made huge hype would probably have never happened.
And if competetive Smashers do one thing extremely well, it's support each other and the games they love. When given the choice of what game to get for EVO via a donation poll for breast cancer research, the Smash tournament community raised
$94,683 for donation. When Armada
was robbed in Las Vegas (in which he lost his cellphone, bank card and $300 in cash), people donated en masse. Competetive Smash is something that is evolved as a niche community but has grown into a hugely successful community.
Nothing is preventing anybody from just playing Smash casually; but kicking the competetive Smash community in the balls because you think it's "not fun" makes you seem incredily petty about what "fun" is. :/"