Ah well, hang on.
There are two different use cases here.
In the first, you're using an instance of Drum Replacer to replace a single item in the kit. Say a tom. And you're either only using one layer in the replacer, or the layers are being used to create a single drum output (eg, layering up three toms to create one sound).
In such a case, you'd generally be working monophonically, and you'd want your layers to be placed together. In which case, it would make the most sense to not use the DR panning, and instead set your panning at the level of the (mono) track.
In the second use case, you're using Drum Replacer to listen to one track, perhaps an overhead, and using the DR layers to trigger multiple items, say kick, snare, and tom. In that case, it's useful to be able to use the panners within DR to feed your stereo track.
So I'd disagree that there's an unnecessary step here. There's a flexibility allowing the above two use cases, and inevitably, there's a decision point for the user to choose an appropriate setting.