At least one forum that I sign onto daily uses
Vanilla. While there have been small updates, the version is basically the same as it was in 2009--and it's pretty robust. New != better.
I'll be honest, that looks like a pretty miserable forum. Heres the thing, if I'm just here to post 'Anyone know where i can find' threads then something like Vanilla might be perfectly acceptable. However, I know in some cases I haven't posted threads or responded to threads because what I want to do or say isn't easy or quick so i figure i'll just do it later when i'm 'back at a pc' which I may forget by then. Sometimes I read this site on my phone and while I can do basic text replies, I can't do anything elaborate. I think in a technical forum like this, it would be great if there were ways to easily respond to things. For instance, as much as I (and most of us) hate facebook, its super easy to post something. I can quickly write a message, click the photo button and select a bunch of photos, then hit submit.. Even doing that on this board isn't the easiest, luckily most of us work with retro computers so we don't mind all the added steps, but I'd certainly wish I could quickly drag and drop photos into my post or even use it from a mobile device easier. I personally think having more features and easier/cleaner web 2.0 interfaces allows us to express ourselves better in our posts, which does allow better, fuller discussions.
That said, i'm not advocating one way or the other whether this site should change software, i'm really just suggesting that in many cases software improvements do enable more things to be done and can improve the experience. I think we can all agree that MS Word doesn't do much more than Word Perfect did back in the day, but I certainly know which one I'd rather use and which one has enabled more people, more use with less training.