I personally consider myself to be a fairly conservative person and while I think that Ann Coulter can be amazingly intelligent, quick witted, and funny at times I think it can also be her own worst enemy.
She's usually right, but if the goal is to make liberals realize she's right, the way to convince them is not to insult them or call for their death in the title or first sentence of the book or article. When people are insulted or threatened they go on the defensive and are less open to new ideas.
If however she is not trying to sway public opinion then what is her purpose? Preaching to the choir seems like wasted energy.
Not from her point of view if it earns her a good living.