The instrument training provided during primary training
is designed to give pilots a way out should they
inadvertently fly into a cloud - not to support a longer flight.

Nothing in the PTS supports this view. Instrument maneuvers are not
classed with emergencies, and they include tracking VOR radials which
certainly implies longer flights than are necessary to exit a cloud
that was entered inadvertenetly.

Note, though, that the FAA's Airplane Flying Handbook (FAA-H-8083-3, page 4-1)
does link basic instrument training with emergencies:

"When introducing basic flight maneuvers to a beginning pilot, it is
recommended that the integrated flight instruction method be used. When this
type of instruction is used, training in the control of an airplane by outside
visual references is integrated with instruction in the use of flight
instruments. When beginning pilots use this technique, they achieve a more
precise and competent overall piloting ability.

The use of this type of training does not, and is not intended to, prepare
pilots for flight in instrument meteorological conditions (IMC). It does,
however, provide basic instrument skills to be used in an emergency. This
type of instruction also provides an excellent foundation for advanced
training for those seeking to obtain an instrument rating."