With (e => method(e)), the arrow function is only redundant because there’s no this context.

As soon as a this context is introduced — e.g. (e => this.method(e)) — it’s not redundant, as the behaviour of the two snippets will be different. To be redundant, the behaviour would have to be the same.

Regarding promises, the rules in the package are RxJS-specific. I’ll consider adding a similar rule for promises to my tslint-etc package, but, for me, it’s not really a priority, as I use observables wherever possible.