In writing headlines for a newspaper, why should the editor use stylistic and linguistic devices?

because it is a rule, the titles must be deep to attract the reader, and depth does not come only with the use of stylistic and linguistic devices.

It is not the editor's job to do so, but individual journaists should use stylistic and linguistic devices to catch their target audience's attention and to enhance their reading appreciation. 

To grab attention I guess. He or she may read it while browsing through the paper. Sometime you may not be able to tell the truth as it may invite criticism I guess