The screenshot feature looks helpful, but taking screenshots isn't really a pain point for us as there are a ton of tools that do this for us and make it easy to drop into Moqups (including a Moqups chrome extension that does exactly this). If you say scrapped my entire site, took screenshots of everything, and gave me a digital copy to work off of, that would be interesting. Alternatively, if your design tools were directly embedded into the site, that would also be really interesting.
These are both big asks, and they might not be feasible, but the more you can close the gap between taking an existing site and turning it into a design space, the more attractive a tool like this would be for our org.