Although a moratorium might have been a good idea, it really wouldn't solve the root problem, which is the complete lack of any check on trial-court judge's power.
As a simple example, once Judge Greer found that there was no possible conflict of interest regarding Michael and Terri, nobody else could do anything to force the appointment of a guardian ad litem for Terri.
I don't know how to fix the system without making things worse, but it's clear that some regulations which are designed to prevent "judge shopping" instead allow whatever party in a case controls venue to shop for a favorable judge and then keep that judge forever.
There are a few specific things that could have been done that would have helped Terri's case, and that might be reasonable to pass as legislation though the usefulness would be limited.
For example, the statute regarding guardians ad litem could enumerate some specific and indisputable circumstances in which a judge would be required to appoint a guardian ad lib, rather than merely using broad terminology. Such circumstances could include, but not be limited to: