Just practising...what are the advantages and disadvantages of owning thousands of toys for a child?

On the one hand Children who have lots of toys to play with may be less creative. If they already have a cowboy costume, a plastic sword to play as knights and a hat to become wizards then they are used to finding everything they need to play already made and ready to be used. As a result, they may not be able to use their imagination and to create an armour for a new adventure with just a piece of paper and a box.

Another problem with having too many toys is that the children Moreover they’ll probably will not understand the value of things. They’ll not won't care about their toys as they know that a new and better one is certainly coming soon. They may not use them properly and they may break them. Furthermore they we’ll will (we'll = we all) always want more new toys and as soon as they see a new toy advertised on television, they’ll want they their parents to buy it. They’ll become quickly quickly become bored to playing a game and they may never feel satisfied.

On the other hand, a well-behaved child who receives lots of toys can experience the world through them. He can learn about colours. He can learn about vegetables and any kind of food playing in a little kitchen made for children. Also, if his parents buy him board games made for his age and memory games, he can learn how to match similar cards. He can develop hand-eye coordination making necklaces with strings and cubes provided with holes. He can discover how doctors’ tools work playing with a toy briefcase full of them. Also, if he has plastic hammers and a hand saw, he can pretend to be a carpenter. (I would develop this paragraph more and talk about how the toys can be used to learn and develop new skills - you hinted at this but didn't develop the idea very well. Below is an example from me).

....second half to come

On the other hand, a child who receives lots of toys can experience the world through them. By playing in a toy kitchen a child can learn about vegetables and different types of foods. With plastic hammers and a hand saw, a child can pretend to be a carpenter. He can discover the work of a doctor by playing with a briefcase full of toy doctors' tools. In addition, if a child receives developmental board and memory games he can learn new skills like colors, mathematics, and reading. For example, by making necklaces with strings and cubes with holes he can develop hand-eye coordination. 

To conclude we all know that toys help children know learn about the world and have fun. Sometimes Nowadays children may have even too many toys nowadays but the quantity is not a problem if parents can manage to make their children understand the value of their toys importance to be always grateful and to take care about of their own things them. As a result, their children won’t be spoiled, even if they own hundreds of toys, but and they’ll grow learn happily by learning through and playing with them their toys.