I think it would be handy to be able to select multiple lines, right-click, and say "create filled region from selection" and "create masking region from selection." This would then open a region sketch and import the selected lines as boundary lines. The user could then add, remove, or edit lines as needed and then finish the sketch to create the region.
I suppose it would also be helpful to have the option to choose whether the original linework would be retained or replaced by the region but I think the main use for this tool would be to replace linework with a region. That would save people from having to create a region with the pick lines tool, then go back and select/delete all the original lines.
