I definitely think so. I don't do it, but I think it's very helpful. If you narrow down what you're looking for by category, instead of going through search, everything's still sorted by recency. And I think that's how a large portion of people look for items, anyway. So renewing still has its place, especially if you're in a category with a lot of competition.
I noticed while doing my accounting that as soon as I renewed three different items, all three sold pretty much immediately. So based on that, and more than just that instance as well, I think renewing really does help. I just don't have the budget for it, so I wait and hope, and my item usually sells once it expires and I renew then. :)