A request for proposal for a specific program may require the company to review the bids to not only examine their feasibility but also the health of the bidding company and the ability of the bidder to actually do what is proposed.
The most obvious reason for using spatial imagery in metaphors is that the language of the primary processes (e.g., dreams) is spatial imagery. This can explain everything, but is trivial: it is always true, and you cannot make meaningful distinctions with it in a text or in changing contexts.
Imagery is the use of descriptive language, which appeals not just to sight but to all of the senses. Imagery often makes writing more interesting through the use of sensory details and can add a layer of deeper symbolic meaning to the text. The images in the poem 'Harlem' by Langston Hughes - 'a raisin in the sun,' a 'festering sore' - make the poem more engaging and meaningful.