The SCJD reflects the process of a real project: following specification, deriving detailed requirements, researching implementation technologies, implementing the application, justifying decision, and creating documentation.
Frankly, the argument contending that the SCJD has less value because it is not an exam taken in a "secure" class-room is incredulous. First of all, a person who really wanted to could somehow outsmart the system on any test. Secondly, any person who did not do his project is quite likely to fail the follow up exam. Last of all, the exam requires research and consultation. If you ask someone or read a book, it is no different. I don't really see the big deal behind research and consulation involved in the exam.
The harder certifications such as the CCIE require some sort of practical work. Why would they include a project component in the SCEA certification?