- It had a table of contents. You can list the contents of a ZIP file, or even extract individual files, without having to decompress the whole thing. (Which was a particularly big deal back in the 90s, when extracting a large archive would take a while.)

- You could update an archive in place. Not incredibly useful, but certainly nifty.

- It had support for multi-disk archives. Again, big deal in the 90s.

Finally, last but not least: it existed in the PC world. Ports of software between UNIX and PC systems were rare back then, and were made more difficult by the fact that the software would have to run in a segmented (16-bit) x86 environment.