Not true. Plenty of people wanted to see Tad die. I've read posts (not on this forum) by people who were so annoyed by Tad's screaming they wanted Cujo to bite his head off.The movie ending didn't bother me at all. It is scientfically impossible for Tad to have lived in the movie, but nobody wants to see a little boy die after practically watching him suffer for an hour IMO. The movie- the latter half of it, anyway- was very intense. Loved the movie and the book.
Plus, there's posters on this forum who think the ending sucked. Did they want Tad to survive? I don't think so. But in these cases, I rather think it's becuase they wanted the film to stay true to SK's nihilistic vision. The movie changed naturalistic intent of the book.