It recently came to light that The Division will feature free post-launch downloadable content, but the specific details on what the content will be has yet to be revealed. As it turns out, one of the features coming to the game after it releases will be a feature that would have been included in the game at launch.
According to Associate creative director Julian Gerighty in an interview with GamesRadar, players will not be able to trade or sell items between one another in the game when it releases. The reason the feature was removed from the game's release version was the "priority of different features."
The feature might not be entirely omitted from the game, trading and selling between players might be added in an update later on. "It’s something that obviously some people are very passionate about," explained Gerighty. "It’ll maybe make an appearance in the future." Whether or not the feature will indeed make an appearance in the game hasn't been set in stone, but hopefully it will come in an update.
Considering The Division is online game that is set around players coming together (for the most part) and tackling missions, it would be odd for there to be no trading function. It's like playing an MMO without being able to share the loot you don't need.