"There has to be some kind of reform that says the jurors cannot do this kind of crap like plan for book deals or profit from the trials."
Why? A soldier can write about his war experience, an airplane pilot can write about his career, an entertainer can write lyrics and chords and strum and sing.
Why should one particular life experience be precluded from compensation?
It would seem that someone with a preconceived notion about a particular outcome of a trial could be swayed to lean one way or the other depending on how they viewed it affecting their book deal rather than based on the facts of the case.
Because the oath you swear as a juror is to the facts and justice, not your wallet. It's not a matter of "Rights", 1st Amendment or otherwise, its a matter of integrity. Should a juror in your trial send you to the gallows in order to get a book deal? That's actually a form of robbery.