Quote Originally Posted by Ultimatecalibur View Post
It is simple but not in the way you think. The Recommended gear system works completely off of ilevel and will always choose the first item it comes to based on where items are in your Armory Chest. If you have something equiped the system will recommend the highest ilevel item that the current job can equip. If there are multiple equipable items of the same ilevel the first item found from right to left top to bottom will be suggested.
I also previously thought this was the case, but have since been told (specifically regarding why this is an issue for ARR tanks) that it isn't specifically about ilevel but the increased sub-stats that comes with it. In the case of tanks, it looks for VIT which is also added to other classes - in lower numbers at the same level, but a higher-level mage robe may have more VIT despite woeful DEF, so it gets recommended.

This also makes sense in relation to equipping jewellery, which is generally applied correctly even in ARR and HW where it is all-classes but designed for specific roles.