I would actually say no to this. I think one of the more fun parts of GMT was working for your items. I remember I actually had a corner of my suite dedicated to rare/seasonal/expensive items. If you can just buy rare items off the market, it makes them feel less valuable to people who waited and worked for them in game. Besides, the Sunabouzu shrine would feel a lot less rewarding if I found it costs $3 after I spent 15 hours in game to earn up to it. I earned those because I liked to play the game, not because I got paid and had leftover money.
If you look at the market, almost all of the market supported games have items that are earned via microtransactions or DLC. The only one I see that does not have any in game purchases is Battleblock Theater. All of the BBT items are very cheap because you can just get the majority of them by normal gameplay. The only items that cost more than ten cents are items that were glitched and were not supposed to be marketable or items won in a steam sale tie in. Because all of the items have no set value from microtransactions, they are very cheap and almost worthless.
Look at CS:GO. It costs $15 too. You could say that the players are put into 3 'classes':
- Players who do not have any skins
- Players who have mostly cheaper skins
- Players who have expensive skins/knives
Sure, you could go and get some good skins by just trading up or opening cases, but that is too hard. The marketplace and trading sites are much faster alternatives. If TU had this, it would make it so much harder to get certain items without simply buying them, creating an economic system with classes and pseudo-microtransactions.
"Now wait!" you may say, "GMT had trading too. It never messed anything up." This is true, but in GMT, trading was allowed only for GMC and GMT items. Players were banned for trading GMT items/currency for other products. This means that you could not convert other things into GMT things, you could only exchange them for their equivalent worth.
TL;DR: The game is more rewarding when you earn things through in game means rather than IRL means, than the market does not work in a game without microtransactions, and could create pseudo-microtransactions