use arrow functions to create class methods with bind operation

Maybe this is out of topic, but still, belongs to bind operator subject. 

Why don't use arrow functions operation to create methods of classes with bind operators?
```
class Example {
  bindFunc(...args) => { // automatic bind with "Example" object
    ...
  }
}
```
It's the same of:
```
class Example {
  bindFunc = (...args) => { // ugly way
    ...
  }
}
```
