If your browser supports displaying title attributes, you normally have to navigate to that particular item in order to see it. For links, you also generally have to perform a different and slower action - such as hovering instead of clicking. So, I agree with jadelennox that it's likely that many users don't know that title attributes exist or how to access them.

I also know that for me, on my browsers that I use, they're not a reasonable substitute for finding an item in the first place. I can skim a page of links a lot quicker than I can navigate to each link and read its title text. And on one of my browsers I can only even see that title attribute if it's on a link - I can't see title attributes on other items.

But as said earlier, this particular instance ends up being solved by style=mine (and related) options.