Why I think that PDSP should be examinated ? Because it's great stuff. If it will be accepted by scientist, it will have much more impact on society - it would be taught in schools for example.
That's not really true. There a lot of useful stuff in psychology that doesn't get taught in schools.
As a disciple science develops around what's measurable.
If you have the thesis that being aligned with the 7 seven principles that Steve advocates helps you to live the good life than you have a few challenges:
1) Measuring whether someone lives the good life.
2) Measuring whether someone is aligned with Steve's principles. How do you transform whether someone is aligned with truth into a number?
3) Personal development is hard work while taking a pill isn't. The idea of controlled studies is that the person who sets up the experiment can control what everyone is doing.
4) Because of institutional blindness it's difficult to get a grant to research something about personal development.
5) It's in it's nature not reductionist. If you do physiology than you get away with saying that you are dealing with system properties that aren't necessary explainable by looking at the parts of the system. I even had a physiology professor speak of energy without being able to tell me about what he meant when one left the system metaphor and moved into biochemistry (but he said that it was probably something biochemical).
In the hard sciences you get away with stuff like that but you don't get away with it in the soft sciences.