I think there is the assumption that engineers will be well equipped enough in their jobs that they can learn and evolve throughout the entire process. Interpersonal skills are something that are necessary in every job and for some people, these skills are harder to develop than technical skills or knowledge. So if you come out of college with a solid technical foundation and outstanding interpersonal skills, through training and research you can bridge any gaps found in your knowledge while being able to function properly at your station. While technical knowledge is usually expected to have a learning curve, interpersonal skills should be exemplified throughout.