Yes, it is much less about the back and forth, the discussion. Which I suppose is great in some cases, but it's definitely not ideal for all.
I will say that tumblr has a nice feature where people can ask you questions and you can answer them on the blog. That's pretty nice. But I wouldn't call it a discussion--I'm sure it'd be 90% "what should I wear to a wedding/interview/funeral/whatever" in your case.
For what you have been posting, and what you have said you want to do, I definitely think a traditional blog is more appropriate. Someone like Vox, I can see why tumblr makes sense for what he wants to do--he can just put what he wants out there (tons of pics, mostly, or very short-form text), take it or leave it.