While I really don't care one way or the other if a logo gets slapped onto one of my buildings, this idea is a definite no go for me.
1. We all already get inundated with too much advertising as it is from every direction in today's society. I have no interest in requesting more.
2. In one world my guild has members from Australia, South Africa, UK, Canada, Mexico, France... just to name some. Most companies aren't so broad in market that they'd have any interest in such a geographically diverse group.
3. Buildings are often rather small on the display. Graphic design elements would make it tough to make an advertisement obvious without changing them to something terribly gaudy. I really don't want to start seeing Vegas-style signs all over my city.
4. Someone would need to be hired to negotiate these advertising contracts. So overhead would go up.
5. Every time a contract is sold, someone would need to design a new building.
6. Every time a contract expired, the existing building would need to be pulled and replaced.
In short, this idea adds a lot of cost and maintenance to the game without adding any value to the player. Even if enough revenue were generated to offset the added costs it still doesn't improve the game in any tangible way.