So we need to add the paper format and margins control groups found in the page properties dialog into Tools > Options > Draw > General, so that a user can set their preferred page size and margins when creating a new drawing.
Draw doesn't have fix page sizes in most use scenarios, e.g. when a drawing is to be exported as raster graphic. And often 'strange' dimensions are uses, e.g. for business cards. We have requests to resize by drag and drop (bug 98950), to automatically increase of the page size to the size of the drawing (Bug 98786), to introduce a manual 'fit page size to drawing' interaction (bug 81118), and - most important and often requested - to allow different slide / page styles (orientation, size) in a single document (bug 49787). The discussion on margins is running in bug 109100.
In the sidebar we have access to all page formats, yet no margins, so the enhancement would be just the default in this dropdown where users request more variability.
Because of consistency the enhancement make sense but the functionality is there.
PS: In general I'd prefer to just store the last selection of those dropdowns (any!) independently from tools > options, which is blown anyway.
(In reply to Heiko Tietze from comment #1)
> In the sidebar we have access to all page formats, yet no margins, so the
> enhancement would be just the default in this dropdown where users request
> more variability.
We have access to margins in the sidebar, which we are discussing in bug 109100.