I assume you mean the Antec 300? Not the 100.
Antec spent a period of time focusing on avenue's that were not deemed to be for the enthusiast market. We worked on products aimed for B2B and corportate environments and as such the Antec brand in the enthusiast segment seemed to weaken. Our line up wasn't that strong in this field for a while I will not argue the point, it just wasn't the focus that Antec was pointing too at the time.
However we have had some top level management changes more recently, and now the focus is coming back to the enthusiast market and I'm quite excited with our new products we have now, consider the P8 and the P110 these are much better alligned to the enthusiast customer. The future with new unannounced products as well will be just getting better and better.
I just want to say "watch this space" as I think in the next year or two will be be back - granted the enthusiast case market is very much different to the years gone, when the 300 was the pinnacle, there is a much wider range of products competing in this segment, Phanteks, NZXT, Inwin, Corsair, Bitfenix, Fractal Design etc. When the 300 was at the height of popularity there were only really Antec, Coolermaster and maybe lesser so Lian Li in this market. Competition is fierce but we welcome the challenge, as an enthusiast myself I just think the more brands fighting it out, the more new innovation will be made - win win for you the user!