Why is the fact that Tom and Jerry talk (and have musical numbers) such a Berserk Button
for the fandom? Yeah, they never held conversations before, but in the theatrical shorts, they talked occasionally and sang all the time. It's not like this was an Ass Pull
on the filmmakers' part.
- It's probably from association with the film not being very good, or indicatve of what Tom & Jerry were about. There's very little of the slapstick that made the original shorts popular, and since the talking and singing take up so much of the movies time, it isn't unfair to assume that the humour of the source material got stripped out in favor of it. Ergo, the talking and singing are bad because they replaced what made the theatrical shorts appealing to begin with.
- Could be the Negative Continuity that the movie implies about the past scenes where they've spoken/sung. The movie makes it clear that neither knew the other could talk, but instead of the few short lines and songs, they talk for the entire movie. Basically, it seems like the movie was disregarding all the old cartoons and treating it like a new gimmick, which pushed away long-time fans.