Why attack dice bonus from upgrades?

[nabbig2]

For example in the rts, howcome the upgrades raise attack dice instead of damage? It makes it very unstable, and it's kind of strange. Is there any reason?

 

[Chocobo]

It's to make the damage not lethal ; also the dice increases base damage if you noticed (min dmg = base dmg+dice dmg ; max dmg = base dmg+dice dmg*spdice dmg).

If it would only increase base damage, it would be useless to upgrade it for high tech, for instance you will see gryphons with 45-55 dmg instead of 55-85? -> would increase armor instead since it's useless to up attack (if it was base damage only).
Dice bonus also increases max damage, so it's not constant damage.