Looking back, one of the biggest mistakes in the 3.0/3.5 editions was the magic item creation rules. This seemingly sensible change fundamentally changed the nature of D&D.
Back in the “good old days”, magic items were strange things. There was no real explanation of how the items were constructed or why a Potion of Climbing cost 500gp where as a Potion of Levitation cost only 400gp. There was a section in the 1st edition DMG that dealt with magic item creations but of the four pages, three are dedicated to scrolls and potions. The remaining rules only cover vague details of how a magic item was created. For example, a cleric had to spend lots of money creating the physical item, place it on their alter and keep praying with a 1% chance per day that the item would gain the desired magical power.
Magic item creation, was in effect, only something super-powerful NPCs could do and thus the supply of magic items was limited. The only items a character ever got the chance of acquiring were those taken from the cold dead claws a monster. This lead to scarcity and frequent arguments over who would get what magic item at the end of the adventure.
Our preferred way of settling this issue was for everyone to role a D100 and the highest got to pick first, the second highest next and so on. This led to situations where characters who could not use any of the items available having first pick. There would then follow some haggling and result in the Magic User picking the +2 2H Sword so that he could trade it with a fighter who had a scroll of 3rd level spells acquired in a previous adventure.
The designers of 3.0/3.5 decided that if magic items existed, there must be a sensible, systematic way of creating them and they came up with an exceedingly balanced and sensible set of rules for it. All magic items were constructed from a recipe of spells. Each spell had a cost associated with it modified by how the device was to function (e.g. charges). Hey presto, a cost for each item was calculated.
This had two major, negative impacts on the game.
It made the game less fantastic because all the quirky items became too expensive. The price of the item was now linked to how much it cost to make, not how desirable the item was. So a Ring of Protection +1 went down from 10,000gp to 2,000gp whilst a Ring of Water Walking went up from 5,000gp to 15,000gp. If your character had 15,000gp in his pocket, would he buy a Ring of Water Walking that you may use once in an campaign, or wait until he had another three grand and buy a +3 Ring of Protection that would be used in every combat?
The second change, was the rise of Ye Olde Worlde Magic Item Shop. As any spell caster could now create potions, scrolls and even minor wondrous items the market was flooded. No longer could the GM tell the players there was no one in the town with magic to sell. The rules told the players all they need to find was a low level spell caster and hand over a few hundred gold coins.
So now when players are examining the treasure trawl from a dungeon they simply add up the price of the items and flog them at a discount to Ye Olde Worlde Magic Item Shop and use that money to buy whatever item they want.
The apparently sensible addition of magic item creation rules has removed all the contention (fun) from dividing up magic items, made players far more utilitarian. Characters are now kitted out with carefully selected items, paid for by all those odd little items that characters once treasured.