there isn’t really anything wrong with Eternal Items. Sort of…
on the plus side, Epic & Legend affix values are doubled, and the Item Quality is automatically +50%
on the negative side, only a few Crystals can be used to modify them.
Eternal Items are strong, aren’t versatile, and are put in a Build As Is, while Legend Items have versatility, not as strong as Eternals, and are put in a Build As You Want.
for most players, it comes down to personal preference when it comes to using Eternal Items or not.