Giving Display Properties its own panel back is better, yes.
I generally find the double row of Tabs in Object properties (and now starting in Viewport Properties > nothing selected) a very poor UX decision. Actually I had already started writing a rant as I first discovered the change, but it was Christmas time and I thought I’d give you a break. But now, as the new year is almost over again – here it goes.
Reasons why those Sub-Tabs suck:
They are a isolated concept, an exeption from the rule.
Only Object properties has them in V5. In V6 you are not trying to abolish this shortcoming but you sneak them in in Viewport Properties too.
Sub-Tabs are visually ugly.
They don’t match the styling of parent Tabs – these are just buttons which load pages.
They lock features in place and that is by far worst of all:
Users thus have no way to rearrange content of sub-tabs to areas which make more sense in their workflow. It happens to me practically on a daily basis that I need simultaneous access to features from one or more child Tab and the parent Tab (Object Properties). This can make some workflows, e.g. in texturing and material creation quite inelegant and way more clicky than actually needed. As I know the program well, I may help myself with Macros and such, but that’s likely not what most users will do. Another really bad consequence of locking functionality in place is that one can’t turn irrelevant stuff off. I’m sure that I won’t ever touch several of V6 object properties sub-pages and now also of Viewport Properties > Save Frames) but I will have to look at them nonetheless. That’s not nice.
Other programs handle this sort of challenge a lot better, among them is Blender. Users may collapse currently unused clusters of functionality within Panels, seldomly used stuff may get dragged to the very bottom of the Panel. One may let some vital feature appear in various places / work contexts or may build entirely custom Panels. Obviously one can reload the default setup as well.
Rhino also in V6 is unfortunately equally inflexible in terms of editing the default GUI as previous versions.
Overwritten default keyboard shortcuts still appear wrongly in the Menus (Make Ctrl+Shift+S SaveAs and
see the Keyboard Hint still appear in Edit/Split). Delayed context Menus still have some default entries users
can’t throw out… and in case someone has the idea to recolour the GUI to a darker scheme this still doesn’t
Page-Item rearrangement in Blender