[Der_Einzige]

Transfer learning is no longer under-investigated. Just look at how the NLP and CV communities get state of the art results

[GlenTheMachine]

Transfer learning is absolutely under-investigated. The current results in CV are awesome but they only pertain to CV. There’s little underlying theory that helps you apply it to other areas. Mine, for instance, which is robotics manipulation.

[throwawayjava]

There's a huge difference between "under-investigated" and "doesn't live up to the initial hope/hype".

It's possible for something to be over-investigated and also not produce results. See also: the build up to AI winters.