Why are time management communication and motivation given more importance in the project management in contrast to traditional management?

I think the question implies that you believe that Project Management is an evolution of normal, traditional management.

Project Management is about a managing a project with a defined length (in time), cost, and specification. Project Management is said to be about 90% communications (thus the importance), as the Project Manager usually has to communicate to a lot of people (stakeholders, employees, etc...), in order to get his/her project done.