When an adventurer begins his career he’s always looking for magical treasure. Even in a magic-rich setting a +1 sword is a coveted item. As the character advances he will seek more items with even higher plusses. After all why stick with a +1 sword when you can have a +2 sword? But eventually the plus no longer matters. Believe it or not there comes a time when the player realizes that the plus isn’t the most important part of a magic item. Eventually an item’s power or ability is deemed more integral to the character than one more plus.
Our home campaign recently moved into the epic tier. During a recent adventure the heroes completed a major story arc and were rewarded with treasure suitable to their level as well as a level 30, +6 bow. Although two characters in the party use bows and both currently have +4 bows neither player was interested in the item. They were content to keep their level 17 and 18 weapons respectively than trade up for a level 30 magic item. These are players that are among the greediest I’ve ever played with (and I mean that as a compliment) yet they both felt that it severed their character better to keep their current +4 bows than trade up for a +6 replacement. In both cases it was because of the importance of the power their current weapons gave them.