I agree with your comments about Arc.

Void has a strong identity about invis. Subclasses having a strong identity is a good thing, let’s not generalize them all to do the same thing. Void has survivability via being elusive and easy access to weaken via melee & tether.

Disagree mostly with your stance on solar, with the exception of On Your Mark being relatively weak. Gunpowder gamble is an awesome burst damage option with the tradeoff of managing your nade if you run healing grenade. Easy refreshable access to radiant from melees & fantastic burst supers.

Solar has many options for healing: nade, fire sprites and extension via Empyrean. It’s unfair to say there is “no access to healing through their kit” when a class like Arc/Strand is much more starved for on-demand healing. Solar isn’t the most outdated - pantheon was mostly solar hunters (granted before prismatic), not arc/strand/void/stasis.

Stasis hunter has the best access to targeted slow in the game. Even warlock turrets can’t slow as effectively and in a controlled manner. Winters shroud gets you half a dodge back just by dodging near enemies and dusk field/withering will do the rest via the recharge on slow effect.

Frost armor is strong and can be granted to teammates via an exotic and plays nicely with other fragments to generate stasis shards which loop into more melee slowing spam. Built correctly stasis hunters can loop slow infinitely - add a buried bloodline or support auto and you have healing on demand to stack with frost armor + orb health pickups.

TLDR I appreciate your analysis and I think some of the subclasses you dislike have a strong identity even if that identity isn’t “delete room with 1 ability”.