I beg to differ…
The Windows file system will set files as read only because the files came from a medium which is read only. This is a measure which reinforces sane handling of the files. The read only flag isn’t even available of ISO 9660 discs, nor is it available with Joliet extensions.
The only method of storing files with the read only attribute (set either on or off) on such formats is to pack them in an archive.
Can you check again by copying some files from a CD? I would be most surprised (and further educated) if they came off the disc with anything other than a read only attribute.
BTW, I’m not sure if the above info applies to UDF and Mt. Rainier file systems but it is certainly true for ISO 9660 based CD’s with Joliet and other common extensions. You can check the UDF specification @ www.osta.org