Worrying about what not to say teaches you how to keep from offending someone. You're less likely to offend someone but it's harder to get your point across
Worrying about what to say will help you get your point across better, but without those donts, you're more likely to offend
The former is like getting a good gun, but subpar bullets. The latter is like good bullets with a subpar gun
I think it is much more important to care about what not to say rather than what to say. How many times have you heard someone in a group make a comment and cringed because it was just the wrong thing to say? People speak without thinking first. You can hurt a person's feelings, alienate people, and end friendships by saying the wrong thing.
I think that people should be more concerned about what not to say than what they are trying to say. All too often it seems as though people are saying the wrong things, and are not using their words correctly or are using words to hurt people which just isn't right.
I believe people should do more to avoid the things they shouldn't say rather than trying to craft what they can say. Doing the later can make a person seem programmed and unoriginal. I believe people should feel free and able to relay their beliefs, but they should understand that they may not be in the majority on some ideals.
If you think about what to say and hence also the effects of what you will say then that is quicker and more efficient. To think of everything not to say would use up all of your time and prevent you from saying anything at all ever. Having to tell yourself in your head "I should not say... OK now what other things would it be a bad idea to say? I must tell myself in my head right now..." It would take forever. It's better to think of something to say and think if it's likely to cause any problems if you say it and if not then say it.
Here's how i see it. If you think about what you're going to say, then there's absolutely no need to think about what you don't say. Why? Because you've already said what you've wanted or what you needed to say. The rest is nonsense. If you think about what not to say more then that just limits what you want to say, honestly. Just try to get your point across. I believe it's always better to speak your mind than to adjust it for some reason. I guess what I'm trying to say is this: Think about what you're gonna say, say it, then don't say anything else if you don't want to.
No, people should not care more about what not to say, because life is too short to not speak your mind. Someone should not be shy about being able to say what they really think. We need to be able to have open and honest discourse, because we can't have progress without it.