Second language (L2) writing researchers have enthusiastically adopted task complexity frameworks in their examination of the effects of complex task features on L2 written performance. However, such research often overlooks the effect(s) of such features on general L2 development as well as L2 writing development. Drawing from Manch?n and William's (2016) perspective of writing as a mechanism for language development, this paper (a) presents a critical review of L2 writing research informed by task-based language teaching and conceptions of task complexity and (b) argues for expanded L2 writing research on task complexity and its effect on L2 production as well as the ways in which complex task features facilitate attention to language, and thus general L2 development, and L2 writing development. Future research is suggested in light of a discussion of research trends to date.