Didactic
Etymology
From Greek "didaktikos," skilled at teaching, from "didaskein," to teach. Praise for a clear lesson easily curdles into complaint about a heavy-handed one.
adjective · /dy-DAK-tik/
Designed to teach or instruct — and, often disparagingly, too eager to moralize.
What it names
It captures the double edge of teaching-through-art: instructive at best, preachy at worst.
Example
The film’s message was sound but its delivery too didactic, pausing every scene to underline the moral.
Related idea
Shares its "didaktos" root with the autodidact; a didactic work sets out to instruct you, whether or not you asked to be taught.
See also