Negative words

People always ask me.."why do you speak about negative things almost all the time?" The answer i always thought was that its obvious. But I think there should be some change in their perception. Because one should think that ones words should make some difference. If something is already positive, you dont need to make any difference. So speaking about negative stuff is definitely not being pessimistic, its more than optimism. People should get used to accept compliments[particularly bad ones] and change.