Some them are more acceptable than others! I've put the zip in the back (two hoopings) as Mops describes, but I think it also works well if you create a flap to conceal the zip then you only need one hooping.
I prefer the one hoop method it is easier for me and I dont mind it in the front. hugs Joyce
I prefer the zip on the back as well and make my designs that way. If you want to do them ITH that means doing the back with zip first, then rehooping, embroidering the design and adding the back. Or as you did, finishing on the sewing machine.
Nothing wrong or illegal skipping the zip in an existing design, that's not really altering it in my view.
That is how I am going to make my eye glass cases. For me personally I like to see the design and the zipper can go across or lenthwise,on the back, which ever you want. I only have a 4x4 hoop so I can't do them as an in the hoop design.
It just looks better I think. Especially when you use up all your pretty colored zippers and have all the dark ones left.