Just because we are using genre and rhetoric does not mean we do away with comparison and argument.  We can do away with the redundant comparison and contrast since comparison implies contrast.  Why not do a paper comparing several genres about similar topics?  I personally am thinking about this.  As for argument, there is no way we are dispensing with argument.  Many articles, books, essays advocate positions.  As such, we as teachers need to bring up argument.  As a citizen our students need to know argument and comparison to watch a presidential debate.  Part of our job is helping students become literate, informed citizens.  They will need argument and comparison in addition to rhetoric and genre. Understanding rhetoric itself implies understanding of argument.