I think shorts are fine for young children, but once the child becomes the “age of reason” where they understand that we should be wearing our “Sunday best” to meet/greet our Lord and one another in a special place, our dress should reflect that! True the Lord may not care what we may be wearing, but we should set standards and try to have a few pieces of clothing we call “church clothes” in our closets! People with limited finances and who are poor are obviously not able to do this. But for most of us, a sense of modesty/decency for mass should be easy. I prefer to put my girls in dresses, and my sons in dress pants with a nice shirt. My husband and I follow suit. When we come home, we then change into our “play” clothes, and everything is hung back up for next week!