What is good battle content?
How would you design Battle content to be interesting?
There are three personal skill types:
  1. Cerebral- Knowledge, what to expect and how to react.
  2. Reflex- The motor skills, physical ability to do.
  3. Resources- The tools, equipment and stats needed to act appropriately.
Good combat has a degree of those things. The reason why combat gets stale is once you already have the knowledge, and a competent motor skill, all three get stronger the more you repeat something. Since combat in most instances here is static, what might feel impossible at first becomes easier, and then later becomes stale.

Dodge this, run here, stack that, space this, face away here, stand there. It seems complicated but each fight for the most part plays out the exact same way in different orders from another fight, but that singular fight has the same strategy whether you do it once or 1000 times.

Then you have people complaining about wanting something different and unique. And when that shiny new event, dungeon,raid, or trial comes out. It fills that desire momentarily but due to the static nature. It too will become stale and the desire will begin in an endless cycle that no developer can satiate within that rule of static.