In multiplayer games, I noticed a lot of people neglect culture structures in favor of trade ports. What are your opinions on this?
Here is my opinion:
Having lots of money from trade is good, but it can be a deadly gamble. If you're spending most of your resources on researching and building trade ports then you're probably neglecting the size of your early-phase ship fleet. This could be doom for your empire if you're attacked early in the game by a larger fleet.
Not only are you allowing yourself to be dealt the quick death by a larger fleet early in the game, you're also allowing yourself to be destroyed by culture later in the game. If your enemy built numerous culture structures and if you built all trade ports then you will certainly lose your planets due to a lack of allegiance. Your empire will crumble.
In summary, if you're going to build nothing but trade ports then you better hurry and build a large fleet to attack the enemy. You can't afford to play a long-term defensive role when relying on trade ports only.
I have decimated a many of Trade Empires through culture.