While runes add few stats (that are not even +1% on the basic stats) the enchants does multiply the base damage of weapons or base defence of armors.
red brawn rune II gives +8 atk vs +10 from one level of enchant.
Green vitalis II gives +130 hp which for a sorceress is over 1/10 of their base hp
yellow vitalis II gives +100 just under 1/10 of a sorceress hp
Yellow guardian rune (the defense rune) II gives +40 def you would need +10 on an armor to get that much def and you still probably wouldn't get to 40 the diminishing returns on armor are steep.
You are really underestimating the contribution of runes to a characters stats.