I meant an A-pose rig, actually, like Ang2, Scarlet, oritginal Bella and, why not mention her also, Genesis8. have.
I saw the images for a moment I thought there would be an alternative Dawn2 with A-pose rig. I understand now that is not the case.
There are many good reasons for developing clothing that features sleeves in 'A' pose. That is how most garments are cut in real life. If they would be cut them in 'T' pose you would end up with a large ball of fabric under the arm pits in the lower arm positions that are most frequent. In real life that is uncomfortable unless the fabric is very stretchy. In dynamic clothing that ball of facets is a sure receipe for trouble and slow performance. Conformers in T pose have huge distortion on the shoulders.
An old Sway I made, based on Bella in the Beta days of A-pose, explains some aspects.
There also is a
pdf for those who prefer that format, but it looks less good.