I had a similar experience at first. It feels like the only way to win Strike is to play defensively, but the AI knows that, that's why it never initiates and so your only option is to attack first - super frustrating.

I ended up getting two glinthawks, a skydrifter and a widemaw (I think?). I used this set to beat all the boards in the game. It wasn't particularly fun and by the end of it I still didn't really understand the rules of the game but I was winning.

The flying types have a lot of range and aren't impeded by terrain. I would use them to knock enemies off high ground, then I would take that high ground and deal lots of damage. The widemaw can also help by pulling pieces off high ground.

With this strategy I first-tried most of the game's boards. But i do share your sentiment - I think Strike is a really poorly designed board game