I understand the logic behind leaving InDesign’s Preview checkboxes unchecked: Rendering complex content or effects could have an impact on redraw times, aggravating users. (Of course, what really aggravates users is having to check those dadgum Preview checkboxes.)
Of course, if you check a Preview checkbox once, it remains checked in future sessions (unless you wipe out your preferences); this gives you the option of choosing how Preview behaves. But why would you not want to preview the results of your choices in a dialog?
But here’s something ironic—there is one Preview checkbox that’s pre-checked in InDesign. It’s the checkbox in the Frame Fitting Options dialog—the one dialog in which you usually don’t have anything to preview, because you’re flavoring empty frames before you bring in content.
You have to admit that’s kinda funny.