Is Bandwagon Effect good or bad?

This is my first time learning the phrase "cognitive biases". Although it sounds interesting, but the more I read, the more I'm getting confused! 

Cognitive biases is a type of error thinking that occur when people are processing and interpreting information in the world around them. It is caused by many different things such as heuristic, mental, social pressure, individual motivation, emotions, and limits on the mind's ability to process information. Cognitive biases sometimes lead to bad decision, however, it is not all bad, sometimes, it allows us to make decision quickly, especially when it comes to dangerous situation. http://goo.gl/nX379F 

Last week, I learned about the 12 cognitive biases that prevent us from being rational - http://goo.gl/ZIw7m . I'm particular interested in "Bandwagon Effect" - People doing certain things regardless to their own belief, because other people are doing them. People tend to go with the flow of the crowd, so that they don't feel that they are alone or left out. 

Some example of this type of bias are, during election, people tend to vote to the most popular candidate without any evidence or facts to prove that he or she is the best. Because many people are voting, so they think that might be the right thing to do so, which doesn't make sense. Another example is when a leader giving a speech, when he finish, one or two people start to give him applause, then follow by ten, twenty and eventually all people in the room. In fact some people might think that his speech is not that good, some might disagree with what he just said.

In my point of view, most people have bandwagon effect. For instance, I-phone. We know that I-phone is very popular, most people use it, that's why we should have one. Everyone has Facebook account, we should have one as well, otherwise we are out-of-date! This kind of thinking that influenced by the crowd, that people are doing it, so we should do the same, without considering if we really need it, or if we can afford it, or if we really mean it.

Another example, in Lao society nowadays, setting a fancy theme for wedding has become a trend. For instance, my friend's wedding theme is blue color. I actually don't want to spend lots of money on tailoring new dress just for this one event, and I don't even like blue color. But because I was one of the bride maids, and my other friends were all happy with this, so I had to do for her because she is my friend, and it is once in her life time, such an important life event! 

In conclusion, sometimes in some circumstances, it is rational to follow the trend, but sometimes we don't have to betray our own belief just to fit in. We should think about our own perspective and consider the facts before going with the flow of the crowd.