Yes and no.
Yes, you want to leave stuff up that helps with SE and is well reviewed, commented, and tagged. But you don't necessarily have to leave up anything that might be hurting in some of those respects.
If you have a few clunkers that are bringing down your studio's overall ranking then dropping them can help boost everything else. However, keep in mind that some of the best traffic in terms of highest conversion comes from those low traffic pages so leaving them up is obviously a good thing not only from the SE perspective. Like everything else, let the analysis of the numbers guide your decisions.
