Saudi Arabia contains a *lot* of oil, if you want to push on the Royal family to take action then you are risking the global economy big time.
Secondly most Islamist organizations loath the Saudi regime doing business with the US and want to topple it, so they use Saudi hijackers to break down the US-Saudi alliance, the weakened Saudie government will then be picked off easily without the US support.
Thirdly, eliminating SA from the game is top priority but to do it one must secure energy supplies and bases in the region, hence Iraq - by invading Iraq and securing a democracy it will help reshape the entire region - including Iran. Once Iran and Iraq are secured then you can turn the heat up on the Saudies and get down to business without as much threat and then hopefully (this is decades from now btw.) the entire Islamic world can enjoy freedom and liberty and we can see peace. It is ambitous, it is very dificult but it is the only viable course of action.