system
Given the following post, respond as if you're commenting on Reddit:
human
[Skyrim] how messed up is Skyrim's economy?

Gold seems to be practically worthless in the ES universe. It's so easy to come by that finding a gold coin is the equivalent of digging up pocket lint. This shit is everywhere! Odds are on an average day of ~~antiquing~~ ADVENTURING you'll scrounge up more than enough to top up Scrooge Mc'Duck's olympic-sized infinity pool. 

No wonder everyone in the game is a bandit and there's only like 20 farmers in the entire country. How horribly inflated is your economy when you don't even bother having lesser denominations of currency? Or when renting a room in some fleabag inn costs more than what an Earth peasant makes in a lifetime? You could argue that coins are just gold-plated or gold ore is super abundant but that's never even implied in the game. 

Then you have every joe-blow wizard who can transmute iron ore into silver or gold! You don't even have to work very hard at it, it's not like you're some alchemist questing after the philosopher's stone or pussying around with some "law of equivalent exchange" bullshit. That said, a chunk of solid gold ore the size of your fucking head won't even buy you a house in the snobby Cloud District. You'll need to pay the GDP of Saudi Arabia just to live in Breezehome, a 1 bed/no bathroom house so shitty it's own name implies it's drafty as hell (not to mention your reward for saving the city from a frickin dragon is being able to *buy* ONE horribly marked up property, fucking jarls). Jesus, is Whiterun just the fantasy version of Vancouver?

So clearly there's some serious inflation going on.
gpt
The main reason that gold isn't as expensive is one you've already listed - Magic. When mages can create gold from iron, the price of gold will drop.  
The truly expensive things in skyrim are the things which are hard or impossible to reproduce, such as enchantments, rare or unique weapons and armour, and potent potions and poisons.  
The recent breakthrough in smithing, Dragon Bone/Scale armour, and the Dragon Bone weapons that accompany these sets, are extremely rare, and can sell for more than the price of a house, especially if tailor-made, or enchanted.  
Why do the peasants worry for food when gold is in such abundance? Simple, as much gold there is in the world, it matters not a jot if there is no food to buy. Skyrim's harsh winters and hardy land make growing food hard, and with the recent rebellion, imports are becoming rarer, and more expensive.  
Breezehome is expensive not because it is extremely large and spacious, but because it is inside the hold's walls, offering protection from bandit raids and the like. You could easily build a home outside the walls for far less, but chances are, before long you would have to fend off bandits, werewolves, or even a rogue wizard or two!  
Also, these left about coins you go on about, are mainly hidden within tombs, ruins and the like, left there as an offering to dead family members, or have been left there for centuries, since the ruin was last sealed up, likely during the ancient times.