I haven't written anything on this topic because I didn't want to make the effort. I will contribute something now though.
Here are the most popular arguments against the use of items.
1. Items introduce randomness into brawl.
2. Items are broken.
Here are the most popular arguments for the use of items.
1. By taking away items we are taking something away from the game. Brawl was meant to be played with items.
2. Items take skill to use. They add depth to the game.
I'll give my thoughts on each.
[Items introduce randomness into brawl]
If the spawn points of the items are unpredictable then items add an element of randomness or luck to the game. Now I've seen a few claims of the spawn points being somewhat predictable but I will ignore this because the added element of randomness doesn't warrant a ban. When someone says they don't like this element of randomness what they're really complaining about is that their edge over a player in a game with out items has changed in a game with items. This doesn't matter, however.
Even in a game with unpredictable elements a player can maintain a long run edge over another, as long as there's still parts of the game he has control over. Let's say we have two players, Scorp and Zeto. In a game with out items Scorp has a 70/30 edge over Zeto, if Scorp plays 10 games with Zeto he can expect to win 7 of those 10 games. However, in a game with items Scorp has a 60/40 edge over Zeto (by the way there's no reason the edges couldn't have reversed). He can expect to win 6 games out of 10. This really bugs Scorp as his odds of losing to Zeto in a tournament Bo3 has gone up significantly.
If Scorp has a 70/30 edge over Zeto his odds of losing a Bo3 is 21.6%
If Scorp has a 60/40 edge over Zeto his odds of losing a Bo3 is 35.2%
His odds of losing the set have almost doubled. However..
If Scorp has a 60/40 edge over Zeto his odds of losing a Bo9 is 26.6%
I did not include the math because it's too long. These particular numbers aren't important, the point is that an edge can be changed with the number of games played. Take Poker as an example. The best players edge over the weaker players is Dependant on the structure of the game. The random or luck factor in the game does not stop a strong player having an edge over a weak one. As far as tournaments with items goes, the structure could be changed until the perceived edge over a player is the same as tournaments with out items. Now this may require so many games that the tournament would take longer then the community is used to, or likes. This is a valid complaint. The problem is a player's edge over another is very hard to measure, especially in a game like brawl. I'll talk a little more about this at the end.
[Items are broken.]
It is very difficult to prove something is broken. In fact unless it's very trivial it's impossible. Examples don't prove anything. They may give us a very strong feeling but it's not a proof. Think about how strenuous a chess proof is, say we're in a chess position and we want to prove that if white plays perfectly he will mate in 12 moves. Well in order to prove this we would have to cover every possible response by black, the proof may end up being very very long, simply showing a mate in 12 moves many times is not enough. In order to prove something like this in a fighting game we would have to cover every possible move for every possible frame. This is beyond our scope as a player.
What tends to happen is two players will begin to theory fight. Present their perfect strategy with an item or character as proof of its brokenness, this is just to simple to be a proof.
So do we ever get to ban anything then? I'll talk about this later.
[By taking away items we are taking something away from the game. Brawl was meant to be played with items.]
Well we really don't know how the developer meant the game to be played unless we ask them. Even then, we may get a insufficient answer. Some argue that since items were on as a default setting that they were meant to be played with. That could be. However it's quite common for the GUI (Graphical User Interface) part of the game to be completely separated from the game play portion. Perhaps the people responsible for the GUI decided that having items on as default would be the most elegant choice. Either way though, we just don't know what they had in mind.
That's OK though, for the sake of argument let's say they did intend for the game to be played with items on. Now one thing we need to realize is, that when you change the settings of a game you're not just changing the game but creating a new one. If the game Super Smash Bros Brawl has items included when you remove those items you are not playing Super Smash Bros Brawl any more, you are playing a different game with a different set of rules. Remember a game is not defined by it's name but by its rules. I always thought a more appropriate name for Brawl would be something like 1000 games in 1. Every setting change you make creates a new and different game.
Now our problem is that Nintendo released Super Smash Bros Brawl with a thousand other games included on the same disc. What's to prevent us as a community to say we don't like brawl, we like this other game that was included with it. Let's play that instead. This is what the Super Turbo community has done.
Let's take a look at the character Akuma in Super Turbo. Is he broken? Maybe. As I stated earlier though, a proof is impossible. This didn't prevent the Super Turbo from banning him however. The community decided that they simply didn't like the game Super Street Fighter 2 Turbo. They liked this other game with a different set of rules, a game with Akuma removed. Now there's nothing wrong with this, in fact it was probably best for the tournament scene. What's to stop the smash community from doing the same thing?
[Items take skill to use. They add depth to the game.]
By depth we'll say that by having items included the decision tree is bigger. Some players may even notice they win many more games with items on then they do off. Is this enough reason to include them? This by itself is not enough reason to have items included. What you can say is that you like the game with added depth. That's fine but maybe other players don't.
What if we added depth to the game of Chess by making the board bigger and adding a piece or two. The decision tree would increase by quite a bit, is it a better game though? I don't know. I can't make an argument for either game. The same goes for the two different games of brawl with items and brawl with out items.
I'm not for or against items. I just wanted to put out this information for both sides to think about. What tends to happen and what will happen with brawl is that majority rules. Whatever the community decides they like is what tournaments will run. Most of the smash community immediately began to practice with all items off, which is fine. They assumed most tournaments would have this rule set and they were right. What I suggest though is people try out the many games included on your brawl disc. Maybe throw a tournament with a hand full of items on, they all don't have to be on. Test a few different rule sets in tournaments and see how consistent the results are. Give it a chance, you may be surprised.