Came to post this.
The so called "RPG mechanics", specially level up mechanics, just don't work with strategy games. I don't mind limited upgrades through equipment or promotions, but unlimited leveling is a game breaker.
To be fair, I think RPG mechanics suck for any game that requires any sort of skill, may the game be action or turn based.
Said that it's arguably the best way to implement difficult. Those games allow a disciplined player will be able to completely customize his difficulty by giving him freedom to choose his handicaps(such as not using certain characters, equipment, etc). Of course this sucks because you limit the amount of content you get despite paying for the full game.