In court decisions dealing with burdens on enumerated rights you often see a discussion, or at least a reference to a previous decision, as to what level of scrutiny to apply. Why, in the case of enumerated rights, is it not automatically strict scrutiny? If the rights were important enough to list, I would expect them to be given the highest level of scrutiny.
This is an opinion question, even if it doesn't seem like one. The life work of many professors is trying to explain the current system of review. One theory that is fairly well accepted relates to the concept of deference to other political actors. To understand this theory, we need to begin by recognizes that the Court is not unilaterally adjudicating political rights; it is one of many actors that all have some stake in making Constitutional decisions. The Court recognizes this, even if it also demands that it get last word on whether or not it gets last word.
In footnote four of Caroline Products the Court laid the foundation for the modern equal protection doctrine. That text embraced a constitutional scheme whereby rights are given judicial protection primarily if they are unlikely to be given political protection by the other branches of government. Under this scheme, we care about groups that are politically weak or political distant from those with power. This equal protection jurisprudence is an example of deferential thinking; we trust the political branches generally unless there is reason to doubt the effectiveness of the political process.
The deferential thinking approach to constitutional law holds that we do the same for many other area of Constitutional law. A given enumerated right is only Scrutinized strictly by the courts if the courts don't trust the other political actors (States, Legislature and Executive), to adequately protect that right.
As I said, that is a theory. Not everyone agrees that this is what is going on or that this is what should be going on. Moreover, many enumerated rights are protected under a very strict level of review. Strict review and "strict scrutiny" are similar ideas, with the latter being a term of art and the former being a reasonable description of how much attention courts will pay to protecting a given right.
Tiered scrutiny has always garnered some level of....well scrutiny....and in some ways has been controversial. A big reason this occurs is to strike a balance between the federal gov't and states' rights and individual rights. Tiers of scrutiny allow the Court to distinguish between strongly and less strongly (and, frankly, weakly) protected rights. It also allows for differentiation between protected and unprotected classes. These categories are a matter of judicial construction throughout the ever changing make-up of the Supreme Courts.
Some members of the current Supreme Court have pushed against precedent in applying long held "tiered tests" to determine the type of scrutiny to apply; and have balked at having to fit a case into formal "tiers," each with its own special "test" (rational basis review, intermediate scrutiny, strict scrutiny, etc).
I was just reading somewhere that Thurgood Marshall wanted to replace the Court's use of tiers with a balancing approach that could be adjusted on a case by case basis. On the current Supreme Court, Kennedy has long spoken out against tiers, and instead applies his own version of a reasonableness test (see Romer v. Evans, Lawrence v. Texas, and others). Much of the Court finds Kennedy’s approach contrary to precedent and frankly unorthodox, although it may be a better approach.
Different kinds of scrutiny for different kinds of rights has been the rule because, for example, your right to property is not the same as your right to speech. You can see how the government's interest in serving the best interest of the masses may override your property rights (10th amendment), but speech or civil rights are of a different ilk.
But if you read the same-sex marriage case, Obergefell v. Hodges, the Court was more Kennedy-esque, moving somehow away from formal tiers and towards more of a "reasonableness" standard. In most cases, however, the tiers will remain because there is a difference in certain types of rights: wealth and things are never going to be as unalienable as when we are talking about the the civil rights of the people.
It bears remembering when and why tiers of judicial scrutiny came into being in the first place. The Supreme Court constructed these tiers not to constrain the protection of individual rights, but to guard against the unjustified interference with the political process. Removing the tiers removes the guard. (Building the Tiers of Judicial Review, Kurt T. Lash.)