Postponing an ICO does not mean that the ICO project is not good, sometimes it will be used as a strategy to buy some more time for the project development and when the project is ready to launch they resume the ICO, to show the investors that the project is ready, the homework finished, just invest and earn profit.
Looking at the current scenario most of the ICO postponed because the investors are not trusting them because of a lot of scam ICOs. So they wait for this negativity to lessen a bit.