Your opinions on WOM pretty much mirror mine.
At a certain point, we could either spend millions revamping WOM which, no matter what, is a tainted title or we could make a really good sequel and give it to our WOM pre-order group for free. We chose the latter.
The problem is that you wanted to make simulator instead of a strategy game, and you did it. There is a simulator of something, but there is no game that you can actually play and have fun. So just a mere expansion will not nessesarily help, the problem is in your / your company's approach to game design.
Say, consider the difference between Sim City and Settlers of Catan (or even better, Spectromancer, but you probably never heard about it).
In Sim City:
Game Rules are vague or never explained anywhere - you don't really know what EXACTLY will happen if you do some specific action. Say, you plant a tree near a residential area. It's supposed to increase a cost of a land, but by how much? Also, if it does, does it really give you a bigger income, more population? How fast that action returns an investment? How efficient per land square or per $ it is compared to other options that give about the same effect?
Very high action cost per a meaningful decision - say, your city is overpopulated and you make a decisioin that you need a new residential area. So, you mark land for residential area, make roads, power lines, water pipes etc. That's probably a hundred clicks or more even if you don't consider that you may need an extra power plant because of power requirments, a school, police station nearby etc.
Decision-making is based on previous experience - game rules are something of a mystery, manual says nothing and game makes 1001 extra calculations per your action, you can't really predict what the hell will happen if you will do something. That is, if you didn't play 100 games already. If you did, you have a vague idea that if you make an action X game usually adjusts it's gamestate to something like Y.
In Settlers or Catan:
Game Rules are clear and precise - say, if you make a city at some point, it gives you resource A with a chance B, resource C with a chance D etc. You can also get resource A by exchanging 3 resources B for it or through trade with other players.
Low action cost per a meaningful decision - say, you have a deficit of bricks, and so you decide to make a city so to have a relatively stable income of bricks. You make a road and place a city at one of the available spots near the source of bricks. It takes only several clicks. You also need recources for it, but there are many ways to get these resources so that's several meaningful decisions by itself, and these actions are not counted in this meaningful decision.
Decison-making is based on game rules in addition to previous experience - game rules state that if you place a city on that spot, you get bricks with a chance X, and on that spot with a chance Y. So, a bigger chance is better, unless it's too juicy target for a Robber.
Your games are usually closer to Sim City while, say, Civilization series is closer to wargames/boardgames. I don't think you can fix it with just an expansion.