How can voters check the power of the judicial branch?
Voters and their elected representatives check the power of judicial branch through nullification. Nullification is the power, reserved to the States and to the People, typically expressed by State legislatures and court juries, whereby the parties simply ignore the offending law or judicial decision. It is perfectly legal and proper, and has a long and sterling record as the penultimate defense of the People's liberty against repression and tyranny.
Why should The judicial branch of the government have greater power to check the legislative and executive branches?
The Legislative branch according to the US constitution has the power of the purse over the Judicial branch. They determine the funding for the Judicial branch and can determine the working elements of the Judicial Branch. The Legislative branch also has the power to confirm Judicial nominees to the Judicial Branch and the confirmation process provides a series of checks to confirm the soundness of the judicial appointee.