This is our screw-up, not yours. When we were debating whether to send this site into beta, I voiced some concern that there was a lot of overlap in the definition. After some debate internally, we decided to go ahead with the launch, thinking there would be enough interest in other Arduino topics to carry the site. We were wrong. However, I still think this site does demonstrate that there is a wealth of knowledge that hasn't necessarily found a place within EE.
I do feel that it is (at least partly) our screwup, but that's not the reason I'm quoting this.
Basically, being a subset scope-wise, we had much higher standards to live up to. It was uncertain if we would even have had a private beta, so once we had one, we should have put more effort into proving that it would work. Our questions/day were rather low -- on its own this should not have been a problem, as Chem.SE had similar stats in its private beta. However, we also had a very small group of answerers, and we had low views.
I don't know what we could have done. Some of us delayed answering to let others answer, but that didn't work much. (Also, on other private betas it is quite common to have 4-5 answers on good questions. Here we had just 1-2). I guess this was just a general problem with the community; only a few had immediate questions to ask. It could also be that Arduino.cc and Google manage to solve most Arduino questions one has, and the site just wouldn't have worked as a private beta.