odt2daisy currently uses the Title from ODF's document properties to fill in the Title field in the export dialogue. If the title in the document properties is empty, the Title field is also empty - this is what happens with most documents. Ideally, odt2daisy should check the (first) Title style in the document if the title in document properties is empty.
If the user fills in a title in the export dialogue, odt2daisy could save this value as metadata in the ODF file.
(I hope I can write a patch for this.)