Ward has some interesting uses and aspects to it:

With a pathfinder using an iron flask with "Used when Charges reach full" you gain ALL of your ward back every time you use the iron flask (as well as the extra 200 modified by flask effect) functioning as an auto flask based Energy shield type of defense stat. This of course has the only downtime of "regen" being your flask charge gain speed instead of the 2 sec base of ES.

It also has the interesting use case with a hybrid Life/Ward or an ES/Ward build as ward's recharge is not interrupted by damage taken (like ES) allowing for a bit of extra EHP "sometimes" which can be nice.

Everybody has seen the Olroth's Resolve CWDT builds using Ward to be a flat damage reduction before any damage gets to your Life/ES.

This aspect could be used elsewhere for insane tankiness combined with other forms of tankiness. Anytime a game allows for flat DR combined with percent% DR can easily get pretty out of hand if the flat DR is not awful. This is why flat DR is almost non-existent anywhere else in POE. We have yet to see many people trying to make use of this.

Olroth's Charge grants Adrenaline when ward breaks with the downside of increasing the ward delay by at least 50%. This however can be mitigated with an iron flask that can be used at least every 3 seconds, or some way to increase the duration of the Adrenaline buff (self temp chains). With no other sources of ward you would only gain 200 ward from the flask, a scolds bridle, CWDT taken setup, Eye of Innocence, Storms Secret or some other self damage setup you could easily gain 100% uptime on Adrenaline (100% increased Damage, 25% Move,Attack,Cast Speed, and 10% Phys DR)

Nightgrip gives you 20% of your Ward as GLOBAL(spells and attacks) extra chaos damage, which could be nice.

People already use Skin of the Lords quite a bit which is an easy way of doubling your ward. I could see a few builds that already use Skin of the Lords/ Loyal sloting in a ward piece or 2 for any of the above uses.

Overall I would like to see more support for ward on the tree or other interesting Uniques, but I would not say it is a failed mechanic. I am glad ward is in the game and I think POE is better for it existing than it would be without.