My suggestion to make trading vs crafting better.

To make the game less pay to win and crafting more competitive with the trade site. Here's my simple suggestion:

Only allow non-crafted items to trade.
If crafting has been done there should be a "crafted" status on the item and you cannot list it for sale.

This way you have to choose whether you want to trade a dropped item or craft on it. It also prevents people from just buying a super uber maxed out item that someone else has crafted.

This will encourage people to do their own crafting and hopefully also encourages GGG to develop the crafting system to give us more meaningful ways to improve items.