Hi Stefan, from what I can see those .obj files with vertex colors are not adhering to the .obj spec, they're using a custom variant.

Basically they're not "official" .obj files since they are putting in extra stuff that's not mentioned in the spec. It's possible that could cause problems with programs that are expecting that the contents of the file should follow what the spec says. But I guess that's why it's something that you have to specifically turn on.

- Michael