With the influx of players it does feel like the market needs a bit of rebalancing so those who are unable to micro the market aren't discouraged from participating in the market. One issue I see is how quantity items are currently marketted, if you remove the way listing is currently, then you would potentially only be able to sell stack items as 1 or 99, which would be rather tedious.
To fix that they would need to recode the system where a player can put X items on sale for Y amount, say 60 for 900 gil each, then another player can say they are willing to pay 1000 gil for 40. So the game looks at what's being sold for the cheapest and gives you the cheapest offers. So let's say the 60 for 900 was teh cheapest option. It would take 40 of them and leave the seller with 20 and then it would give the hold of 40k and take 36k away giving back the unused 4k.
So basically a blind market where you can look at the history to see what the item was sold for, and then attempt to add in gil to buy the product and if it goes through you get it for the value that the player set.
Say for example, you want a piece of gear and there are 10 sellers. It's a new item and you don't know what the going rate is, so you decide to do say, 5 mil for the piece of gear. The server checks the prices and notices the lowest price is 900k from Seller A so you buy it for 900k and get the 4.1 mil returned to you. You wouldn't get to choose who you are buying from , and an undercutter wouldn't be able to set an absurd price to snatch the "free gil" since it isn't working under the idea that if you say 5mil and the person was trying to sell it for 900k, they get 5mil, nope, they get the price they set and nothing more.
I think if they could design a system like this, the market wouldn't be as toxic as it currently is, it's sad to see how easily the market can be manipulated by those with gil because they have nothing to lose, meanwhile those trying to make gil struggle to keep up, when those with gil can deal with the gil loss because they think of the long term of discouraging others from continuing to attempt to play the market.