Magic Items: You Are Your Stuff

Recently playing a little of the "roguelike" computer game Brogue, I was struck by one aspect of its stripped-down design. You are guiding a character through a dungeon, but the character has no variable stats, no levels, no class, no race, not even a name. The powers of this adventurer derive entirely from the items found in the dungeon - magic items to wear and wield, potions that increase strength and health permanently.
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He's a bro. He's a rogue.

This brings up loot-based enhancements in a tabletop game. Players' characters can get more powerful and specialized in three ways: through automatic level-ups in the rules; through choices they make in leveling their character (feats, options, spell choices and the like); and through loot, spells and enhancement found in adventuring. While the first two are in the player's hands, the last factor is the GM's responsibility. 

At the same time, especially if you're running a stripped-down system where class choices are few and customization options limited, AND if you put a lot of special flavor into your magic items, the items can end up helping define the character - a dwarf with boots of leaping and a +2 shortsword/dagger combo; a priest with a necklace of lightning bolts; a henchman fighter who prefers a pole arm with a purple worm tooth blade.

So, not just power but fun gets placed in the GM's hands. Let's just dismiss entirely the notion, from later D&D editions, that item gain should be programmed and expected, level by level, as part of a "build." The essence of my old school approach is presenting a world that isn't always built around the saga of the PCs. But some technique needs to apply to these choices. It's one of the most difficult balancing acts in the game.

I suggest an average - not a guarantee - of one permanent and two expendable items per every three character levels of advancement, for each character. This should not be a sure thing for the players or the GM, either, and I find it's better to let magical treasure come up semi-randomly or as a result of other people's modules you use (with appropriate pruning) than to put yourself in charge of rationing out the players' fun. In practice, I've tended to stick to these limits, plus buyable "special" items, but if anything being a little stingy on the expendable stuff.

Is it too much of a coincidence that most roguelike games - including Brogue - go for approximately equal ratios of the three classic item categories: potions, scrolls and permanents (armor, weapons, rings, wands)? That is, a 2:1 ratio of expendable to permanent items?