The only time I made a plushie with removable clothing was H-Man's Mieu plushie with the wedding dress that could be ripped off.

Generally speaking, if I wanted all the clothes to be removable, either 1) the clothes would have to be pretty loose, and I think that would look sloppy, or 2) I'd have to put snaps/velcro/other closures on there, and depending on the design, that would make more work for me (and my prices would have to go up

).
So the short answer (which Xander already provided) is: nope, the "zipper" is just for show!
Thanks for your kind words!