By impermissibly substituting his own judgment for Ms. Granville's, the superior court judge's application of the Washington statute became unconstitutional. If Ms. Granville had tried to bar the Troxels from visiting their grandchildren completely, it is entirely possible that the Court would have reached a different conclusion. It's also worth noting that not all of the Supreme Court justices agreed on this issue. The rest were as divided as many people probably are on this issue. In one concurring opinion, a justice argued that the statute itself was unconstitutional, and should have been overturned.
Many states have laws similar to Washington's, including Indiana, Kentucky, New Hampshire and Utah.
These states recognize that parents do, indeed, have a fundamental right to care for their children, but find that this right is far from absolute. Government, they note, limits parental freedom in many ways that affect children's welfare in the absence of specific harm, including the power to require vaccinations, to control school attendance, to prohibit child labor, and to require the use of seatbelts and car seats. These states don't see grandparent or caretaker visitation as a severe restriction on the right of parents to control the upbringing of their children. Preserving the right of children to maintain strong bonds with their grandparents qualifies as such a reason, making grandparent visitation statutes constitutional under this standard. Given the Supreme Court's decision in Troxel, it's likely that parents will attempt to challenge the laws in states with statutes like these.