I disagree that the gameplay is particularly shallow. The end game requires both mechanics and tactics. That said, the end game may or may not be _rewarding_ as

I disagree that the gameplay is particularly shallow. The end game requires both mechanics and tactics. That said, the end game may or may not be _rewarding_ as it's very grindy and there's a good question (for many of these sort of games) of what you're grinding _for_. But the gameplay mechanics get deeper than what you seem to have experienced.