It's probably for a number of reasons, but I suspect a lot of it has something to do with our inability to communicate effectively these days. We're so reliant on doing research or finding our answers by bashing a few words into Google, and we keep in touch with friends primarily through Facebook, WhatsApp or the occasional text message. As a generation, we have moved away from the spoken word and our ability to argue effective has suffered.
This, mixed with the fact that our society is based on building up friend counts as opposed to true friends means that we typically would rather be agreeable to everyone, even if we do disagree with someone or something.