No one said it is "big" deal but it is a deal. +1, thanks, haha posts are important expressions, but not useful information. Therefore we have a tool to express those sentiments without creating more noise. No one wants to see an update in a thread and read "haha". But the poster you are responding to appreciates the sentiment.
The CEOs of Facebook, Twitter, Snapchat and Two Bills Drive all sat around and made these decisions to clean up the internet.