There is more in his character than simple honesty.
They are satisfied with a simple life.
I am not so simple as to believe that.
This problem is too simple.
This work is simple enough for me to do.
That's opportunism pure and simple.
This might lead us to believe that a simple culture would make use of a simple language, that a complex culture would make use of a complex language, and so on.
He is not as simple as he seems.
I should say this is too simple question.
I'm not so simple as to believe you.
With this one exception, it is quite wrong to suppose that a simple culture will also have a simple language.