Rather than arguing the merits of a template versus the merits of a monster, let's actually look at the
3.5 Zombie template and compare two creatures to see what kind of difference you actually get out of the thing. Let's say we use an Elf and a Half-Orc.
Size and Type: Same for both creatures.
Hit Dice: Same for both creatures
Speed: Same for both creatures
Armor Class: Natural armor is the same for both creatures.
Base Attack: Based off of HD, and therefore is the same for both creatures.
Attacks: Same for both creatures, except for Elven weapon proficiencies.
Special Attacks: None for both.
Special Qualities: Hey look, this isn't even described clearly. Appears to be the same for both creatures.
Saves: Same for both creatures.
Abilities: 4 of them are the same for both creatures. The Half Orc has 2 more Str than the Elf, and the Elf has 2 more Dex.
Skills: None for both.
Feats: Just Toughness for both.
Alignment: Same for both creatures.
Result: The only meaningful difference between the graceful elf becoming a zombie and the brutish, boorish half-orc becoming a zombie in 3.5 are their Str and Dex scores, and even those are barely different.
The thing about the zombie template is that it really isn't that useful -- it doesn't
adjust monster properties as most templates do, it simply sets them to the same value every time, whether this means dumping special attacks and qualities, hard-coding 4 of the 6 ability scores, dropping feats, or eliminating skills. This is hardly the only example. A Zombie Gnome is a Zombie Halfling with 2 less Dex and no bonus to thrown weapons. A Zombie Dwarf is a Zombie Human with Dwarven Waraxe proficiency and +1 to attack versus orcs and goblinoids. If you decide that a Warforged has a sufficiently skeletal structure, you can make a Zombie Warforged that's exactly the same as the Zombie Human except for his built-in armor. (And then what do you do if he took the Adamantine/Mithral Body feats?)
Zombies are pretty much the same, even when you
do use the template. That's kind of iconic for zombies anyway -- they're faceless (literally, sometimes) members of a mob, utterly unremarkable from each other. The template further muddles things by not being very clear what gets retained and what gets dumped in the infamous catch-all category that is "Special Qualities."
Would a zombie template be useful? Possibly, though not likely. Is the current one useful? Not so much.