Here are arguments and examples explaining why it's valuable to get "recent" sorting in basic searches (more examples by other Delicious members welcomed).
Knowing what are the new bookmarks responding to a specific question is deeply usefull to keep in touch with brand new sites discoered by a few people. Recent on tags is not enough because lot of people don't make extensive use of the tags or forget important words for other people.
For example
http://hyperscope.org/, http://www.apml.org/ and http://tagjag.com are not found in a "OPML" recent tag search. But they are found in an "OPML" basic search (without "recent" sorting.
When I want to know if anybody have found a new service to mesure blog audience... I only have the solution to ask through the tag (it's already a good thing but not enough). When you search "blog" and "audience" in the tag search... you only have one answer. But you have 1638 results in basic search with a lot og interesting answers.
If I could sort this by "recent", Icould discover the most recently added...

Serge