Well, I don't see it. So there you go.
But I don't think creative decisions and production techniques that were the best they could do at the time necessarily show something as having "aged badly". The idea that a tv show could have accurately predicted how the year 1999 would look is just silly. What it doesn't do is look like 1974 - it's a great projection 25 years ahead.
I don't think 2001 is an unfair comparison, as Space: 1999 was probably trying to emulate its look. The effects are definitely comparable. And the acting is way better.
I think the effects in Space are the best I've ever seen in any tv show. They've got a depth and solidity that seems more real to me than all your flashy CGI stuff. Maybe it's just what I want to see. The design and the effects aren't there to be a documentary portrayal of the future - they're there to serve the story, and they do that fantastically.
I'm sorry, but Space 1999 looks INCREDIBLY dated. There is nothing about that show that does not scream 70s.
I think that made 2001 appear more timeless is that its done with a more 60s aesthetic that was a bit more conservative than what was done in the 70s. The more conservative the future the more likely that it will come closer to the real asthetics of the actual future.
The more "futuristic" you make things look, the more dated it will look in the future.