Individual posts should show the date on them when using a Display Format that currently shows dates on the index.
A matter of consistency, really.
A few users have also requested it.
When Display Format is Blog, show dates on the post itself, formatted to the locale of the post.
When there's a title: display the date, with a special little subdued styling below the title.
When there's no title: display the date at the top of the text, styled the same as the body text.