The 4000 was an excellent machine for its time, but its time has since passed. Twenty years on, its graphics and even its font are terribly outdated, its abilities, while fantastic in the 1990s, seem very restricted now, and its abilities to change are practically nonexistent. The last change that I know of was to the more square (yet still old) TWC logo, lower-case forecasts, and a change to the radar screen font. After that, I think TWC has just stopped any plans to update it (quite right), and only supports the data feed to it now.
The Jr. is better than nothing, but that's where it ends. The III was discontinued because TWC saw no purpose in spending a lot of money to upgrade a machine that was already 20 years old to meet new FCC regulations. And, other than the fact that it still works and has graphics in addition to text, the 4000 is pretty much at the end of its lifetime, too. Sure, it can go on for another 20 years, probably, or so long as the SD feed exists, but it's never going to grow past what it is now, unlike the Intellistar and (possibly) the XL.
I would be quite unhappy if I had to watch local forecasts generated by a 21-year-old machine every day. Believe me, I LOVED the 4000 when it first came out because it was so much better than what there was before. But it has since become so incredibly outdated that the only reason to keep it is for a small cable company to save money and not upgrade. Other than that, I can think of no reasons at all to favor the 4000 over something newer.
Yes, I do miss the days when the 4000 and even the III were used and when I saw them every day. But that's only nostalgic value. I also miss TWC actually focusing entirely on weather forecasts. I'd love for THAT to return, but... one can only hope.