XHTML preparation with li, b, i

Why does HTML 4.01 not require a closing </li> for the <li> tag? It
requires the closing segment for other container tags (e.g., <p>
requires a </p>).

If HTML 4.01 is to help us get ready for XHTML and XHTML 2 does not
include the <b></b> and <i></i> tags, why aren't these tags deprecated
in HTML 4.01? Check out the element index for HTML 4.01; they are not
deprecated.

Thanks!