Is there a reason for the differences between the UI for Grid and Guides ?

a) Guides are visually "on" by default - but there are no actual guides. Menu "View->Guides" initially does nothing - since there is no guide to show/hide.
b) Grids are visually "off" by default. Menu "View->Grid" creates and shows a grid if there is no grid.
c) Guides are created/deleted via the Edit menu
d) Grids are created/deleted via the Document Properties dialog.

Comments in the code refer to some sort of backwards compatibility

// show guides if not specified, for backwards compatibility
// hide guides if not specified, for backwards compatibility

Propose to change the Guide UI to match the Grid UI as below.

1. Guides would be "off" by default (if not specified in the doc)
2. Toggling "View->Guides" would create guides (same as "Edit->Create Guides Around the page") if there is no existing guide.
3. Add a button : "Document Properties->Guides->Remove Guides"
4. Remove menu item : "Edit->Create Guides Around the page"
5. Remove menu item : "Edit->Delete All Guides"