[dragonwriter]

> My theory is that Myers-Briggs is more popular among laypeople than Big5 precisely because it's less scientific.

My theory is that it is more popular not directly because it is less scientific, though for a closely related reason--because its so heavily marketed by the private firm behind it and their army of certified consultants, which has created lot of visibility (much of which is at least one step removed from the marketing, so that people are often not directly aware of the marketing.)