When writing Bugmonkey scripts it's hard to parse the html to find just the right element you want to modify.
Let's say that you have a custom field which is meant to store id numbers of customers in your CRM tool. In order to convert these to links with bugmonkey you need to parse the html to find the correct element in order to replace those ids with urls. The result seems to be hit and miss depending on how the page was rendered.
If, however, the custom field had an id attribute which could be used as an anchor (for example to be able to find directly on the page with getElementByID) it would make writing these scripts a lot easier.
Although in this case I'm talking about custom fields, I'm sure there are other places where this could be useful.