I concur…

“Neither work well. Try searching for a post from a few months ago. Nothing turns up. Here’s what I think the problem is. Every Tumblr page is titled with the name of the t’log. You might have noticed that smart sites like TechCrunch, Ars Technica, etc. use the post title as the page title. Doing this lists a site higher on “the Google”, or in Tumblr’s case, indexes the tumblelog at all.”

…Tumblr’s (not yet present) ability to name the pages that are created when you post would be a great first step toward really “having” it.