I don't think anybody with money and time should cancel no matter what happens, not even if the ads are bad, not even if the reviews are bad. It's a unique experience. There is nowhere else on earth where you can stay in a space hotel. You do it because you can afford it. If it doesn't turn out to be interesting enough, you can always run to MK for the day; you are in Disney World after all.
The Starcruiser does look lamer on the trailers than I imagined, but I don't see why it matters. From the first moment of booking, you know you will be doing stuff like playing cards and building model ships. You know it's an indoor cruise ship on land with no pool. You go to relax, eat blue shrimp, and pretend to be in space for a couple of days.
I also don't understand why Disney removed the last video trailer. The Genie+ trailer got even worse responses, but you don't see Disney being ashamed if it. It is what it is: for an indoor cruise ship, that's as good as it's going to get. People need to know that's what they are getting. If they don't like it, they don't have to come. But it's important that they know what they are getting so that they don't get there and then make a scene or sulk or complain the whole time, ruining the mood for everybody else.