RE: Nerf to unplayability all units with Destroy Target
I do agree that ranger does lock out lots of minion structures, but at the same time I do worry that lots of minions structures without a ranger would be completely inpenetrable without tanking your morale in some way. Like you mentioned you don't know whether 1 cost axe is op because of destroy metas, but I do think there's a high chance that it would in fact be op, such as this sort of thing:
(Pretend the wisps are some expensive pieces like vamp+++ or something cuz i dont have these pieces)
Itd be pretty difficult to breach this with no ranged/magic and a line of samurai even if you manage to trade some of the samurai 2 for 1. And if you're running even more expensive minions then you heavily tank your morale even with a 2 for 1 (samurai+0 isn't even THAT expensive) . I kinda worry that having some sort of range/magic is essential anyways for armies due to setups like this, so taking out range destroy would just make everyone switch to the other options like thunder+EE or something
It's hard to say for sure since some of the counters to two axeman like that cause terrible design issues themselves (Behemoth). Also like you mentioned it would be possible to rework destroy effects to give more compensation to the one whose pieces are getting destroyed for free, but in the particular Axeman case, Freeze/Petrify/Wind/Siren can serve as solutions to this with counterplay.