People get rid of them because not everybody has spare ZIP disks around and ZIP drives are known to not only have high failure rates, but to take disks with them when they die.
You are far better off just getting a USB flash drive. Much sturdier, more reliable and compatible with pretty much any year 2000 or later computer.

If you want to use zip disks for backward compatibility with older Macs then I do totally understand that and I even have a USB ZIP100 drive for that. But just make sure each disk is backed up to some other type of media.

Use em if you like, but just be careful and always have a backup.

Yeah, having 4 front facing usb ports would be a lot more useful than a zip drive.
The whole point of a portable media format is the fact that I can plug it in anywhere. No one uses Zip drives anymore, and their storage capacity is a lot lower than a usb drive.

Seems pretty obvious to me: replace it.

Although, currently, I'm strapped for cash. Here's what I plan to buy though:
Front Panel replacement: http://www.sourcingmap.com/inch-internal-front-panel-port-usb-hub-p-27750.html
PCI card: http://eshop.macsales.com/item/IOGEAR/GIC251U/

See if a local PC shop has one with a NEC chipset for $15 or something.
You can also get ones with tiny PCBs instead of the massive one you linked to.

Also, if you buy one from a PC shop avoid VIA based ones like the plague.

Have the face plate custom made, thats what I did. There is a shop near where I live in NYC that laser cuts plastic and its pretty cheap, I replaced almost the entire front of my G3 Smurf with a custom cut face for $50. I am sure the small piece for the zip bay would be much cheaper to have done and it would be perfect.

http://www.canalplasticscenter.com/index2.shtml

They take jobs via email and send you the result.

My results were very worth it:

http://gallery.me.com/mordaskyt/100013

Very sweet Mordaskyt.