Often the only advantage melee really have defense wise over casters is Epic Defensive Stance, most every defensive attribute beyond that comes at the cost of DPS, don't look at tanks and claim all melee are unkillable while FVS gets to have as much HP for free and while Sorcs, Druids and undead casters get immunity to a bunch of mechanics.
Because melee need to itemize even more stats than a caster they can often end up lacking in saves, or resistances and gearing a hybrid like an EK can easily end up being truly glass cannon.
Let's be real here casters truly are top of the pack and repeatedly caster players have screamed at every single perceived nerf for the last couple years "Stat squish will kill casters", "ED revamp will kill casters" and all we've seen as a result of these is casters are every bit as dominant as they were before, if not moreso.
I don't think it is actually feasible to nerf casters enough to even the playing field, not without some truly major shifts. It's also not like melee doesn't do enough dps, it just lacks the utility and front loaded damage that nukers have and it probably isn't possible to bring up melee utility to compete outside of making warchanter actually able to dps.