There shoud be a disagree button for ideas/suggestions. Sometimes it is not enough to have a approval/👍 button. Sometimes it is important for the community to communicate that a suggestion should not be supported.
In the meantime, feel free to voice your opinions in the comment section of ideas - that's where we often find the most valuable insights. Just be sure to be constructive, share examples of specific use cases to support your opinions, and help keep it a productive exchange.