All these ES6 features (and many more) may get you excited, but there is a catch here. As we mentioned before, not all browsers fully support ES6/ES2015 features.
In order to be able to write this new JavaScript syntax today, we need to have a middleman which will take our code and transpile it to Vanilla JS (http://vanilla-js.com/), which every browser understands. This procedure is really important in production, even though you might not think so.
Let me tell you a story. A few years ago, a co-worker of mine began using some cool JS features that weren't fully supported by all browsers. A few days later our users started complaining about some pages of our website not showing correctly, but we couldn't figure out why. We tested it on different PCs, Android phones, iPhones, and many more, and it was 100% functional in all our browsers. Later, he found out that older versions of mobile Safari didn't support his code. Don't be that guy!
As you can see, some times...