For a variety of reasons, but primarily these three:
1. It replaced a classic, which was infinitely better (imo) and appealed to all ages 4 to 75.
2. Like the Magic Carpets, it's exterior destroys the themeing for the entire area. It's architecture doesn't fit. They took a beautifully designed building that was made to support the entire Future World visual concept (for lack of a better phrase "The 80s view of modern/futuristic") and replaced it with a abomination that completely clashes with the surrounding area, and
3. It's a "thrill" ride that isn't thrilling. You sit in a car, go through a factory, and the speed tops out at 60 mph. As has been stated in numerous threads, I exceed 60 mph (in my own car that I get to steer - how thrilling!) every day on my way to work; it's not that exciting. In fact, if I'm not going 75, I'm generally irritated and annoyed.
They took a jewel and replaced it with coal. It would be the equivalent of having a dozen roses in a vase, having someone say "eh, roses may not be as popular as they once were" and taking one out and replacing it with a dandelion. On it's own, it may be interesting to look at and fun, but it doesn't fit. And once you've experienced it once (one puff of air), it's not nearly as interesting again.