Usage patterns
通俗的な〈物〉a popularized/commonplace ~ (novel, explanation, etc.)
This book depicts history as a popular novel.
〈事〉が通俗的だ~ is commonplace/unsophisticated
His opinion was criticized as being too commonplace.
〈物〉に通俗的な人気があるto have broad, mass-market popularity
The movie gained broad popular appeal.