Ogres have
best STR/STA and
frontal stun immunity helps when you're trying to FD with a half dozen mobs beating on you.
Iksar for literally ever other reason including
regen,
AC, more mana than ogre/troll (admittedly still not as much as erude/dark elf, tho), and
Greenmist.
Velious class specific armor rewards do not follow iksar plate wearing rules.