Economics is a big deal in Roleplaying games, no seriously! Particularly in original D&D where treasure was the primary source of Experience. Characters typically need thousands of experience to level which means they will be hauling in vast sums of gold, and that's a problem. Why? Well because cash is a resource, and too much cash trivializes some great adventures.
I read a wonderful book titled "The Name of the Wind" by Patrick Rothfuss earlier this year. The primary tension in the story was how much money the main character needed to survive and subsist and how difficult it was to come by. When he finally achieved some financial stability a lot of the tension dissipated, the very same tension that was driving the book forward and keeping you the reader enraptured. The clutch of poverty is a driving force in a good deal of fantasy and cinema ranging from Cugel to Conan or Sanjuro (Yōjinbō) to Zatoichi.
Let's take a look at a plotline in Zatoichi's Vengeance. A wandering Ronin returns to town seeking to buy the freedom of a selfless girl he fell in love with who is currently indebted to a scummy Brothel Owner. The Ronin is unable to pay for her freedom but he is willing to use his skills for the new boss in order to earn it. Naturally, the boss sends him to kill Zatoichi. If the wandering Ronin was as freakishly wealthy as your average above level-1 adventurer this never would have happened. The price of his love's freedom would be nothing more than a mere trifle, and that's a shame. So, the economy of exaggerated wealth hurts adventures.
It also hurts treasure. You see when your players routinely come across large sums of money, keep in mind that a gold piece could be a fortune to your average peasant, it devalues the money you are giving them. This leads to escalation where player's expect more from their chests and DM's are quick to oblige. Its why you see so many cheap and common magic items in newer editions, to pad out an otherwise boring treasure containing enough money to ruin a hamlet's economy. If instead gold pieces are few and far between then they become the primary source of excitement. If your players are fighting tooth and nail for every last scrap and coin they come across they will actually be overjoyed when they come across eye-widening riches. This takes the burden off the DM who is often pressured into putting something 'unique' in a treasure pile which more often than not is another light on the Magic Item christmas tree. This in turns allows your magic items to be unique and memorable and that's always a good thing.