Why the TBD Devastator aged so quickly

Why did the TBD Devastator become obsolete so soon after entering service?

Aircraft generations moved quickly, and the Devastator was overtaken during a normal three- to four-year replacement cycle.

Three or four years could separate aircraft generations during the interwar period. Rapid technological change explains the succession of torpedo-bomber types in the 1920s and 1930s. An aircraft could therefore be a capable contemporary design and face replacement only a few years later. The Devastator's short period of competitive service fits that development pace.