Statues in Castle Clash

What's the purpose to have statues in Castle Clash?
Looking the picture below, we have 4 different statues (in order from left to right.):
Frost Witch ( 1,000,000 gold), Ninja ( 2,000,000 gold), Thunder God ( 2,000,000 gold) and Centaur Chieftain ( 4,000,000 gold).

These decorations are extremely important in game mainly for two reasons:

1. Placing towers on the map, they improve the defense of your base. This means impose a longer route to the enemies that are attacking your base.
2. All decorations can be sold for 50% of their value/price. This observation is extremely important for saving golds inside the game. For example, if you have collected 500.000 golds but you can not spend them, you could sell the Frost Witch statue, take it back 500.000 gold and re-buy it. In this way the percentage to receive attacks it will be reduced.