1) Meaningful outcomes are really hard, and research is piecemeal. As a researcher, I know I have to publish intermediate and smaller results, because I can't get grants for bigger studies without a track record of publication. This is the way science is done today. Without an angel to just give $15 million for a study of an idea with no track record, you have to build the justification for longer-term studies paper by paper.

2) Placebo-controlled trials are not appropriate at all times. You can't placebo-control yoga. What's placebo yoga? For acupuncture, they placebo-control by putting needles in random places; for pill studies, you get a pill of indeterminate content. For yoga.... well, you know you're doing it. That may be part of the benefit. No getting around that.