I think it depends on what you do, and your horse. My appy filly has a thin, miserable mane, but it folds perfectly over. If I keep it trimmed to about 3 or so inches long, it looks like I spent hours pulling her mane for western pleasure or something. Naturally not a hair out of place, perfect. If I let it grow out, it gets straggly and gross.
I've had horses before with naturally thick manes, and cutting them short looks ridiculous, and pulling a thick mane like that would be awful.
I even knew one horse with a thin neck that rubbed his mane off one summer, so we roached it. By the fall he had 2-3 inches of new growth and it looked SO much better. The extra bit of mane sticking up made him look like he had a much thicker neck and was better ballanced over all.