I wouldn't mind if an observation tower of some sort was installed again, but with newer features. I don't know if they would though, because of Space Spiral's low ridership and I thought I heard that Windseeker was a suitable replacement, even though no cameras are permitted on it.
Also why they didn't do anything to Space Spiral besides blow it up, is because the foundation goes ridiculously deep and the age of it. Was impractical to do anything besides what happened to it. It'll forever be there in a sense cause of the foundation. They only scraped about 6ft off of it when they were prepping it for Gatekeeper, but a majority of it is still in the ground.
Intamin is still making them though, with the new 500ft tall one being installed at the Texas State Fair. Tallest ride again in the park is an observation tower, anyone?