The 3e game designers appear to over-value abilities which cannot easily be taken away. The Monk class is as under-powered as it is because a monk is very independent of magic items--sure, like all classes, they do better with items, but unlike other classes, their effectiveness does not take a huge dive if you manage to divest them of a weapon or divine focus or spell component pouch or instrument or animal companion or what not.
Which is all well and good if your campaign features an awful lot of "You get stripped of all of your belongings and have to escape from a dungeon naked" situations, but that's not most people's experience.
Generally speaking, most groups may have had fun once with a "You don't have any spell components and need to rummage through the farmhouse to see what you can improvise" type of scenario, but consider themselves satisfied to leave that play style alone.
Unfortunately, what I would consider the core balancing principle behind the monk ("Here's a class that is more powerful than the rest of the party if everyone's naked, but less powerful when everyone's fully equipped, so equal on average.") meshes badly with one of the challenge balancing principle that became more explicit in 3e ("We assume everyone is fully equpped, and we even define what we mean by that.")
.
