In the 70s Dr. John Lilly developed techniques whereby pretty much anyone
could have an OOBE. He then carried out the research you propose. Alas,
it turned out that people weren't actually leaving their body, they only
thought they were. What they saw when they "went somewhere" was not what
was actually there, but what they thought should be there. So it didn't
replace airplanes.
There was an explosion of scientific investigation of 'altered states of
consciousness' during the '60s and '70s. It didn't pay off with the
massive progress its proponents hoped for. The altered states turned out
not to be real useful, except possibly for psychotherapy, and all the easy
and reliable methods of alteration involved abusable drugs which the
government has chosen to suppress. What techniques from that period are
still in use? Hypnotic psychotherapy, meditation and acupuncture
anaesthesia are all I can think of, and none of them have had very big
effects on the world.
I suppose one could have predicted that altered states would not be
massively superior to the standard state, given evolutionary
considerations: if it was easy to change the structure of our minds in
desirable directions, evolution would have made the states switch on and
off appropriately, without requiring vast efforts to achieve them.
--CarlF