The way I see it is like this: Wealth or Influence is used to purchase things that may not effect your gameplay versus other players, but may enhance your personal taste for the game. Thus, things I could imagine fitting into this category would be stuff like personalized decor for you flags and uniforms, mini campaigns and missions that are awesome, but not in anyway necessary, etc.. not stuff like new special units, upgrade bonuses, free battalions, or ready to fight wizards.
Wealth/Influence is purchasable with real money, but if a player enjoys the game and plays a lot, he will gain enough W/I to get much of this content anyway.
I think it will work as long as the developers do not cross that line of ifluence being able to affect gameplay.
"Yes... I am writing a book. So far I have the page numbers." - unknown author.