>Ideas need time to be explored, and given a chance.

sure, and the time for that is before you bring them to potential critics.

unless a meeting is intended as a brainstorming session where any thought, no matter how unformed, is welcome, meetings are not a time to present your initial unexplored thoughts to colleagues, bosses, or other departments. take a couple days, think about it without spending other people's time, try to imagine people's objections and have answers to them. then present. shouting things out in a meeting before you've considered and come up with answers to the most obvious counter-arguments is just a time-waster.

You must have very different kinds of meetings than I do. Unless you're going into that meeting with a rehearsed PowerPoint presentation, or there's a strict agenda that doesn't allow any time for exploration, I expect to hear imperfect-ideas-in-infancy. One of the reasons we have meetings is to allow collaboration to happen. It's a format for working together.