but a game that works good in MP also works good in SP.
Boy are you totally wrong. Some of the best SP games are games that are "out of balance". Master of Magic is a prime example of a game that isn't balance for a multiplayer experience and one of the BEST solo single player experiences even today. Plus, many games that have multiplayer have been RUINED by balancing multiplayer and then the SOLO AI becomes horrible because it cannot compete in a "balanced" game world. Civilization games have proved out of balance works and Spartan by Slitherine has proved this as well and Age of Wonders:Shadow Magic proved what happens when you "try" to balance multiplayer and RUIN the Single Solo player experience.
Stardock games like Galactic Civilization I & II series and now even Elemental;War of Magic/Entrantress prove there's a better world and gaming experience when you don't put any or too much effort into the multiplayer experience. There's just not enough multiplayers out there to waste those resources. It's been proven time and time again the multiplayer world isn't very big when it comes to these types of games.
It just doesn't work as you cannot have a balanced multiplayer game and a competent competitive AI in the solo single player game. There ALWAYS has to be ADVANTAGES and HANDICAPS for the AI for the games to be challenging and competitive to play against the AI and balancing the multiplayer game just doesn't do it for the AI.
So what needs to be done and more resources put into above and beyond all else is improving THIS AI and making it more challenging and more competitive before even looking at the multiplayer experience.