Certainly a good point for sure.

But (Im speculating here), I dont think that is the sole reason behind it. They include a battery in the handle, so it can be used without the external, and as far as I can tell, that battery is not replaceable (I havent taken it apart to look... yet). I mean, if the only reason was to replace when gone bad, they wouldnt need the internal, and they could have just repeated the battery type and placement of the IT4.