Yes, it is strange to sew them opposite of what we normally do. And no, I've never pressed seams open or to the side before. I sew the seams at 1/2" and then take scissors and cut them, then wash and dry the quilt a few times til it properly rags to the point that I am satisfied. They are neat and look pretty impressive.
I'll have to admit as a "seam finisher" the whole idea of a rag quilt where you actually clip the seam allowances and then purposely fray the seams...it was different to me--and went against all I was taught in sewing class.
However, they do look neat.