This is really more of a feature request. I LOVE the Title letter count and Description letter count - plus the snippet preview for WordPress SEO as it appears on posts and pages.
It would be GREAT if this could be implemented on SEO -> Titles page.
You say that "For some pages, like the homepage, you'll want to set a fixed title in some occasions."
But the reality is that using a specific title/description on the homepage is the most important place to use one for most people - and if you're not using a static page for your homepage, this isn't the most intuitive place to put this or the most intuitive way to display it.
This is one thing that All-in-one SEO makes much more clear and lays out better, but I think it would be easy to make this better on WordPress SEO.