I would like to be able to apply filters and sorting independently when viewing questions.
For example, if I go to the MVC3 tag and click the unanswered tab (a filter), it is sorted by most votes, and I can't change the sort to, say, most recently active.
Alternatively, if I click the active tab (a sort), it shows all questions (unfiltered), sorted by most recently active.
It would be nice -- maybe for users that exceed a certain reputation, to prevent confusion for newer members -- to have the option to have custom, or at least independent, sorting & filtering.
Ideally, the tabs would be either a sort or a filter -- not a confusing combination of the two.
Again, I'm sure this decision was made for simplicity of the UX, but it's at the expense of a functional UX. And again, if simplicity was the driving force behind the decision, then open the option for those with more reputation.
If, however, this is about performance/caching, then personally I say -1 for performance over function.