As long as we have a "UV Editor", would it be possible to add the ability to rotate the patterns?
The reason this would be a good idea is that Substance Designer and the Substance materials (*.sbar) are oriented along the X axis. Substance materials are the dominant material source for almost all 3D professionals now.
If we had the ability to rotate patterns from the Y-axis to the X-axis, most of us could avoid having to put our clothing into a 3d app, such as Maya, simply to rotate the clothing so that a Substance material can be correctly applied to it. This would save a big step in most people's workflows.
And, I LOVE Marvelous Designer! It is a wonderful application!