I had look at Debian packages provided from the following page

http://www.zabbix.com/download.php

and I found that packages are in very bad shape (according to Debian quality standards).
For instance packages (of release 2.2.2-1) were not built in clean chroot and as a
matter of fact they FTBFS in clean chroot due to incorrect Build-Depends.
Just from the brief look there are multiple FHS and policy violations,
serious BUGs, pre-built source-less binaries, etc...
Packages produce tons of Lintian warnings and use outdated build tools.

According to changelog Zabbix-Debian packaging was forked from
official Debian-Zabbix package as of August 2011 (over two years
ago) – this is somewhat ~400 commits behind official Debian-Zabbix repository:

http://anonscm.debian.org/gitweb/?p=collab-maint/zabbix.git

But I'm not only concerned about incompetent packaging. In fact
Zabbix-Debian packages are binary incompatible with Debian-Zabbix
packages. Apparently nobody on Zabbix side is tracking Debian changes – as result sub-standard Zabbix-Debian packages are provided from the Zabbix web site.
I consider this situation unfortunate for Zabbix users on Debian.
Numerous drawbacks of this situation are brilliantly summarised in the following page:

https://www.zabbix.org/wiki/Appeal_against_public_upstream_packaging

The above page provide detailed overview of problems and provide suggestions for current situation.

Because Debian-Zabbix packaging now includes "java-gateway" there is no need to provide Debian packages whatsoever.
Debian packages from Zabbix web site may be considered obsolete as they provide no
advantages over Debian-Zabbix packages but ship the whole bunch of regression bugs and other problems.

**I strongly suggest to remove Debian packages from the Zabbix
web site**.

Is there are any reasons for Zabbix to maintain its own Debian packages?

In any case by dropping Debian packages you can do a favour to
your users as well as to reduce the maintenance burden and duplication
of effort.