It's true. What could i to say else ......the obsolution of an entire class of weapons makes the game less varied and... colourful. This needs to be addressed. What'd you say?
There are two moments which makes a shield not usable, in my opinion.
1. Shield is a specific item which does nothing except Defense stat boost in global. While it's a weapon, it's not a weapon, but only a method to create additional gear slot. And this slot can not be used otherwise than to Defense buff.
It makes shield usage ... static.
2. Since defensive mechanics was changed with dodge and, later, even with regeneration, the role of Defense is strange ... The role of the shield has greately decreased.
If we dream, there could be an active skill to work with a shield only. And a good position for it could be the War Cry position (Or Down & Dangerous as a variant).
I think both defensive and offensive types of that skill are in demand.
It could be something like Dirty Tricks if defensive, except not through blinding but through something else.
It could be something like Hamstring (or exactly renamed / moved Hamstring) if offensive.
The other way is to increase the shields damage.
And the third way is to make a skill, which allows to use off-handed passive gear (Let's say "ring", "totem", never mind) instead of off-handed weapon. This skill could be used by many builds, and so, there could be a different types of that "ring", but not only "Defense Ring".
So, for example, Iron Jaw (Arms & Armour) and Sweep (Shadows & Myst) could be replaced with that skill.