I’m not much of a word stickler, but I do object to people confusing the word “simple” with the word “simplistic.”
“Simple” means, well, simple: uncomplicated, straightforward, easy to understand.
A simple design is clean, but it can also be clever. Sometimes a simple solution takes a whole lot more thought than a complicated one.
“Simplistic,” in contrast, is oversimplified, dumbed-down, and probably stupid from the get-go, like the idea that building a wall on the Southern border will solve the immigration problem.
I often see students describe the poems of Emily Dickinson as “simplistic,” and they’re nothing of the sort. Dickinson writes
"Tell all the truth but tell it slant —
Success in Circuit lies
Too bright for our infirm Delight
The Truth's superb surprise
As Lightning to the Children eased
With explanation kind
The Truth must dazzle gradually
Or every man be blind —"
Dickinson’s poem is simple but quite profound. The rightness of what she says stands up to close scrutiny; the more you analyze this or just about any other Dickinson poem, the better, and more true, it gets.
I think students use “simplistic” instead of “simple” because they want to sound smarter by using a word that has more syllables.
Academics probably helped create this problem by camouflaging their simplistic thoughts with complicated words.
But conflating “simplistic” with “simple” is, itself, a simplistic solution to the hard problem of writing about complex ideas in straightforward ways.