Those who will not hear the word of the Lord...

...will hear the word of the Lord. Isaiah 28:14 Wherefore hear the word of the Lord, ye scornful men, that rule this people which is in Jerusalem.

The word of the Lord is a simple word.
Isaiah 28:13 But the word of the Lord was unto them precept upon precept, precept upon precept; line upon line, line upon line; here a little, and there a little...

The simple word is despised and rejected by the scornful leaders.
Isaiah 28:9 Whom shall he teach knowledge? and whom shall he make to understand doctrine? them that are weaned from the milk, and drawn from the breasts. 10 For precept must be upon precept, precept upon precept; line upon line, line upon line; here a little, and there a little:
The arrogant drunken leaders in Jerusalem (see verses 7 & 8) seem to mock the simple message of Isaiah. It is beneath them. These who fancy themselves PhDs do not need (read "want") a kindergarten level lesson (content) in kindergarten style (expression). They are chewers of meat, not suckers of milk.

The simple word is deferred and replaced by a senseless speech.
Isaiah 28:11 For with stammering lips and another tongue will he speak to this people. 12 To whom he said, This is the rest wherewith ye may cause the weary to rest; and this is the refreshing: yet they would not hear.
The simple word is from their God for their good, an agent of rest and refreshing, yet they would not hear (Cf. Isaiah 30:15). Alec Motyer notices, "When the simple intelligibility of the word is refused, divine judgement falls in the shape of the unintelligible." When they reject what will benefit them, they receive what will judge them.

The simple word is enforced and accomplished by the sovereign God.
Isaiah 28:13 But the word of the Lord was unto them precept upon precept, precept upon precept; line upon line, line upon line; here a little, and there a little; that they might go, and fall backward, and be broken, and snared, and taken.
God's word is simple. God's word is truth. It is unchangeable and inescapable. It goes forth from God and will accomplish his purpose and pleasure (Cf. Isaiah 55:10-12). In this case (Isaiah 28:9-13) that purpose concludes in judgment.

The word of the Lord is simple, straightforward and inescapable.

[Note: Idea derived from an outline in The Prophecy of Isaiah: an Introduction & Commentary by J. Alec Motyer, page 229.]