Here are some of my feelings about copying - and I do NOT feel drawing is one of my strong skills, but I'm getting better!
I do observation drawings with the littlest kids. I also allow kids to use references when they're drawing - because I know I can render a more realistic animal, if that's what I'm going for, when I have a reference, instead of drawing from memory. Sure, the real thing would be great too, but it's rarely available in the average classroom. So, I'm not sure I see a huge difference between copying and using a reference.
I've been taught that it's easier sometimes to squint when drawing from observation, because it flattens objects and reveals tones better. It just seems that that is basically what using a reference is doing for kids - helping them to render something from 2D to 2D, which is easier for them initially. It seems to be a confidence builder for many - then, after that method, sketching the actual objects doesn't seem like such an overwhelming leap. This seems to help especially my middle school students, some of whom seem to think their work is worthless unless it's realistically done, even though we talk about styles, and reasons for drawing and painting realistically, abstractly and non-objectively, etc. Sometimes I suspect this is due to comments from parents who don't know how to react to kids' art that's less then realistically rendered - and kids pick up on that, and think only realism is "good art".
Does this make sense? If not, I'm open to suggestions - as I said, I don't feel this is my strongest area. By the way, we also do upside down drawings, and kids are usually amazed at themselves, but still often have a hard time getting into "left brain mode".