I know many users that need this information, and it's not because a plugin/theme asks for it. If I had one major gripe with WordPress, it is the removal of this info from the admin pages. While it doesn't have to be a default, I don't see why there shouldn't just be screen option to display it.

I get questions about how to find the ID (usually for categories, pages, and posts) often more than once a week. It's a rarity that it's because one of my plugins/themes need it.

Several WordPress functions (template tags) ask for it. I suppose I could list them all here, but it's easy enough to find these functions in the Codex.