I don't think that deleting the Sandbox is necessarily a solution, but perahps a little more mod regulation of the forums would help.
For example, I love that we're free to start threads at will and it's a nice luxury, but I think it gets abused at times. I don't think it's necessary for someone to start an entire new thread because they bought a few new pieces and had to exclaim it to the world. In most instances, at least one thread already exists dedicated to items and forum members can share their score in the respective threads.
I don't know what it would take to accomplish it, but perhaps more indepth organization to the boards would also decrease the likelihood of repeated threads. As an example, Rebelscum forums have a section for Sideshow and within that, sections for each product line, so it's very easy to track down what you're looking for without too much digging. In the SSF Star Wars section, there are so many random, short-lived threads that bury others which leads to new threads because people weren't interested in digging further to find the old one, and I'm guilty of it myself. If for instance, the Star Wars section had categories like 1/6 figures, PF and Statue, 1:1 and such, people might find what they're looking for with better ease and just continue to contribute in a single thread about a piece.
That's just my thoughts anyway, do with them what you will.