It makes sense if they don't want to cannibalize their own profits for expanding a category of their own products.

I don't really have a horse in this race because I don't care what accessories Apple sells or doesn't, don't buy retail, and rarely buy electronics or durable goods new. I still have a 3 year old pair of QC35 (I) that has had ~10 ear pads, the top band, and battery replaced by me.