It doesn’t make much sense for it to have any tax at all seeing as the game already soaks 80 silver per star. Lets say there was no tax, the upward end of what a player could make off of it would be based on the npc repair merchant, and the lower end of what a player would make profit off it is based on the price of the repair kit. If they wanted to have further control on how much money a player makes off of it they had values preset into the game to control it, there isn’t a need for any tax. You can consider the price of the repair kit to be a pseudo tax.
If they stripped the 50% tax there are still two sweet spot values that the player would need to sit between to be making money off of it. If the player tries to go above this sweet spot value the worth of repairing via that players shop would be based on how much time/effort/cost it would take to back to town to repair vs using that shop. Which is actually really cool, all this 50% cost is doing is dulling down what is in theory interesting.
I am all for IMC controlling player profit via manipulating the cost of materials and merchants, this 50% tax is a seemingly lazy answer to something that wasn’t even a problem to begin with and actually kills the classes that utilize shops in my opinion.
Edit: On a related note I felt like it was a hugely wasted potential to strip alchemist of potion throw. Especially seeing as we can’t trade currently, it would have given the player the option to throw their potions (thus potential profit) to play the role of a healer or damage dealer. This was the appropriate way to allow for crafting based classes to still potentially bring something combat wise to the game.