Yes, there's lots of older content on On Demand. You mentioned WCW which hasn't existed for almost 15 years so, of course, it's all old stuff. If you want to see something more recent, you can find the latest Summer Slam and Wrestlemania events, just to name a couple. There's also a category for Raw and Smackdown events. It takes a bit of patience to go through the various categories to find something recent. They all start with the oldest programming, then go up from there. Personally, I think that's backwards. I would like to see the most recent events at the top of the list.
I don't find the On Demand channel that interesting. I watch Raw and Smackdown on Sportsnet 360 every week and all the PPV events on the WWE Network on channel 512. The WWE Network has lots of interesting programming, depending on your preferences. It's worth spending some time looking around. One of the real interesting programs is called WWE Beyond the Ring and the Steve Austin "podcasts" are really interesting as well.