The listing of tokens on exchange does not guaranty the investors that price for the tokens would grow. People must use the tokens that their price would grow.
That's true, but at least listing is the first stage for the coin to get recognize and to satisfy the investors that the team are doing their job to provide liquidity on the coin. When it's on the exchange, they can continue developing the project and if they do a great job, demand will be created and it will be easy for investors and traders to buy since it's already accessible in the trading site/s.
Demand will increase only when there are active developments and updates. It will easily help the coin to increase its demand in the market. People are investing in potential projects only because they will make some with the bonus they are getting at the time of crowd sales.