Young people have a better ability to initiate a positive change in their communities. They have better technology. They could use technology to grow and expand and build up their communities.
First of all: the stance is for young people's ability to bring positive change in their communities. Second: your question was a little vague. Are you arguing whether it's important for young people to initiate positive change, or whether they can?
Kids are the future! As new generations advance technology, they also further develop our acceptance of new ideas and cultures. These are important aspects that forward the human race.
Throughout the novel there are circumstances in which Gatsby shows he is modern such as his clothes, his car and even his house. These are all things that are different from other for example Tom who is old fashioned and the opposite of Gatsby.