Need roll not possible.

[Kerberon]

The shield itself is not important. That was just used in the screenshot since it was the item dropped from the last boss.
Meaning that I could take the screenshot like I did, without wasting the groups time doing so.

I didn't want that shield, I couldn't care less for it since it was clearly for a caster. So I had no intentions of rolling need on it.

The question was about the greyed out need button, since I didn't get that the game displays all classes that in theory can equip the item.
Had it only displayed the classes that would actually benefit from the stats, the casters, I would never had thought that I had stumbled onto a bug or may have changed something somewhere in some options by fault that made it so that I couldn't roll on gear at all.
Especially since it also happened on all other gear drops in the instance that either displayed GLA or disciple of war on them.

I even asked the group about it, and they couldn't give an answer so I came here.

You're not getting it. Just because there is no restriction on strapping on a piece doesn't mean it's appropriate gear for the class, this applies to everything you're talking about. All the tool tip means is that you can equip it, not that you nessecarily should.