Sure it is useful: you can extract a description, packing list, etc. without decompressing the entire archive. Another example is for making multi-platform packages (For CDs only, of course) and not having to extract every file. They aren't free software? Info-ZIP afaik is DFSG (I think thats it, its been awhile since I was a debian user ;) ) compliant.. Nobody seems to care about the license anymore.