Accomplishments of the items from the roadmap may be delayed, but the team should give updates on what's going on. Because without any news, people will wonder if they are still working behind the curtain or not? There will be negative speculations and all so I think, if you hold ICO and collect some funds from the investors, you have the responsibility to at least give them brief updates if you are still alive or not.
Anyway, the investors should do their own inquiry also because it is their money that supposedly has been used to deliver the objectives of the project.