There are some use cases for the tooltips widget
If you need to put some html code into your tooltip, then just assign the escaped html code to the title attribute, it will work.
<li title="<b>Some</b> <u>html</u>">...</li>
Images can has tooltips too. You can use ether title or alt attribute to keep the tooltip text.
If an element has an id attribute then the related tooltip element will have the same id but with the -tooltip suffix, so you can customize them separately.