As far as I observe, many mediums pertaining to the portrayal of people, such as but not limited to "traditional" porn, has demonstrated its capability for its audience to develop an attachment with the person of portrayal. This attachment, however unilateral it may be, can qualify as an elementary form of relationship. It seems to me that porn, as much as its primary purpose is instantaneous sexual discharge, has further thrived from a kind of emotional attachment, i.e. crush, by its audience to their actresses of interest.
As much as the initial purpose of obtaining sex robots may be likewise to traditional porn (sexual discharge), it tangibility will likely enhance the formation of relationships. This time however, the “crush” will become a motive that one can act upon.
P.S. How is a sex robot different from a doll asides from being electronic?