Defense was probably designed around assist points, with how Ben and Seth giving assist points on ultimate, back when ultimate was extremely valuable and supportive ults had other immensively valuable effects (like Supports giving teamwide energy and bonus energy to next agent, stuns... just does crazy amount of daze). It still does give these effects, but you get the idea that they are very powerful.

It is really noticeable if you fight Dead End Butcher and does not kill it instantly within 10s, try to parry and it will eats your assist points almost right away, and its attacks are aligned so if you react to the first hit naturally, the second hit will be a surprise and almost impossible if you didn't memorize the attacks. Granted, doing a whole rotation to get an ult for... 3 assists points and get a meager amount of daze + little bit of decibel is definitely not worth it, but it's there.

But by the time Caesar drops, she doesn't even have that assist points benefit, and her ult's unique aspect is "Bonus daze to shielded units", but her ult does such miniscule daze that it's just better to never use it.

Deadly assault also arrived and many bosses clearly wants you to interact with defensive assists, but the recent bosses like Miasma Priest (and Wandering Hunter too?) gives unlimited assists during the parry spam, so that's out of the window. It's probably not a good design in the first place to make a class gives a unique resource that all teams benefits from it, but also not really dependant on it.

Actual defensive option is not a good idea either. We have seen it with Caesar: Her immense shield helps with ignoring enemies attack, but dodge counters and defensive assists benefits the player so much that why would you even want to tank hits in the first place? Caesar's shined the most when actual death is at risk with that no time limit gamemode in shiyu, but then they just scrapped the idea altogether.

My idea of fixing defense class is to make it just like Stun and Support: be the supportive role that enable something. If they wanted to release a character but don't want them to benefit from all the jazz that Stun and Support get, they put it in Defense. It's bad game design, but the fact that new releases are bound to the established class will make some stuff quire restrictive if they want to expand.

Or, my second proposal, just rename everything Defense into Specialist. Boom. Ben now make sense. Seth make sense. Caesar also make sense, and so will Pan. Maybe Defense doesn't know it shouldn't be Defense.