On-deck cargo ships are not as common as you think they are. I mean sure, they're everwhere, but they're also VASTLY outnumbered by the amount of roll on/roll off ships. While they are for utterly massive ones, those massive ships are forced to dock at massive ports that have the infrastructure pre-built. Most of the world doesn't have those massive ports or they have smaller ports that are closer. There are a massive amount of cargo ships that are instead a 'roll on/roll off' type, similar to a ferry. That's what this ship is. The minimalistic design is odd but likely has far less to do with aerodynamics as it does with structural integrity and the fact that it's a cargo ship. It's also a concept image so any visual design could be left until the final stages, provided it doesn't impact hull integrity. It doesn't need a bunch of random designs on the outside. All other cargo ships are done in a streamlined fashion. The length of this cargo ship is actually 200m and the length of the sails are 40 meters. They're also sails and not wind turbine blades, are retractable, turn 360 degrees, tilt and designed to be retroactively attached to multiple other ships.

Source.

Seems pretty practical to me. It's almost like the people who designed it knew what they were doing.

This trend of looking at something, making wild assumptions based off of no data, and then judging based off of those assumptions without ever even attempting to verify them? This really needs to stop.