It would make psychological research easier, because you could just directly monitor the internal perceptions of the person rather than have to rely on surveys.
I could be mistaken about this next part, but i am fairly sure i am not mistaken.
I am not sure whether this exists as a natural ability or whether the receivers or transmitters of the imagery must have some kind of technology to interface with the brain, but IMHO There are strange looking humanoids with flying saucers and they are able to control the internal and external imagery of some humans (maybe all humans for all i know) fairly directly. I am pretty sure that they can read minds too, not just send.
They seemed to have read minds. They responded immediately with the phrase" Oh no he is not angry" when a boy started to get scared when he heard one of them start grunting. Maybe they were just so intelligent that they could see the fear on the boy's face.
But regardless of whether they can read the mind of an unaltered human, it is clear to me that they have the ability or technology to cause a vivid voice to be heard in the mind of a human, so vivid that it is more vivid than that same human is able to imagine unassisted. This occurs while they are standing nearby, usually right in front of the person. It is just like they are talking to the person except the voice is heard in the imagination very clearly rather than in the ears.
Now if this natural ability or technology was availiable to both parties they could have a "telepathic conversation"