[In one established tradition (style) from the early D&D days including aspects which have been epitomized and immortalized by the likes of Gary Gygax et all...]
I am often generous in awarding treasure to the players in my group, but only when it "makes sense". That is to say: "intelligent" creatures that wear garments and use tools may have things on their person, but beasts and such might only have discarded items in a lair or its like. That is aside from whatever might be at a specific adventuring location.
In the fantasy settings prevalent in my campaigns, because wealth is rare among the masses, the players have to find special people--merchants, nobles, temple keepers, wizards, etc.--with whom to trade. I do pay attention to the guidelines for max wealth for dwelling size, and max transaction price. Also, the players have an incentive to craft magic items because they rarely can buy or trade for them. They must discover/win them or make them.
We all grew up in the heyday of the "Monty Haul" campaigns and learned that overindulged fun could sour quickly. [god mode in a game?]
Some amount of managing wealth (I don't micromanage or sweat the small stuff) gives the DM:
- Another knob or dial to control overall balance and fairness
- Additional plot opportunities involving individuals, guilds, etc. [taxes, fees, penalties, etc.]
- A way to challenge/thwart the players by requiring them to have reasonable means to transport and secure items of much weight to value ratio
- A way to "drain" unbalancing wealth by having exchange rates for bulky, low value items with the much prized and coveted (small, lightweight) gems
- A reasonable hook/enticement among several others for quests
- A "treat" effect when items of great value are won, recovered, awarded, etc.
For the players:
- There is a verisimilitude with real life and how wealth provides some of the finer material comforts
- A sense of "value" when choosing some things over others, especially when having sacrificed and saved up to gain a treasure item that provides uniqueness, prestige, power, etc. [they can't have everything they want]
- The "satisfaction" which studies show that people tend to have when their wealth is greater than that of others [an example being that the least wealthy person in a rich community tends to be dissatisfied; the pleasure is in the perception of relative wealth]
- Wealth is another resource to be skillfully/effectively managed as a means to an end which is character advancement in an organized manner on a (hopefully) level playing field with other players [also involving donations, loss when crafting, etc.]
- Destruction or loss of wealth whether intended or not is a negative consequence met with dislike which triggers strategic and tactical reactions
- Opportunities to trade, barter, borrow and so on from fellow PC's because wealth is a limited/managed resource
I admit to having, upon occasion, hinted to delaying PC's that other powerful creatures have learned of this change in world affairs as the days go by and they try to process a vast, recently "liberated" hoard in the middle of nowhere [the greed of dragons is legendary, and their means of learning about new acquisition opportunities is positively mystical!].
Lastly, as an aside, I always found it amusing (as likely intended by Jack Vance) when Cugel the Clever in the Dying Earth was always trying to find fine repast and lodgings at inns without having sufficient means due his nature, activities, and fortune. Such frequent penury also led him into whimsical and dangerous encounters. [The "Spatterlight". The million year regression by spell (time travel) to recover an alien being he ate at a wizard's construction/summoning site because he was famished and nobody would feed him, etc.]
I do realize those are literary devices and situations, and that they do not always lend themselves to group-based role-play as opposed to established fictional narratives (with actors, consequences and so on set to parchment and not game-play interactive [unless you are playing a game system in that setting!]), but I do like there to be some challenge available to see what the players will do.
What is that saying about valuing that which is scarce?