Originally the studs were "swedged" which is another word for "rivet," basically. You must remove the swedge area off the studs to separate the drum and hub, or cut off or drill out the studs. There is really no good reason to have them so. Leaving it "loose" like the rears causes no problems
This guy is using a 5/8" hole saw as a "swedge cutter"
http://www.sweptline.org/forums/viewtopic.php?f=20&t=34020