Unless it’s DRM Free, there’s no way I’m buying a manga digitally. I have a bookshelf filled with manga and some even has localised stuff to my language; I can give any of them to a friend if I want to. I can’t do that with any copy with DRM.
People already pirate the fuck out of this medium already; it’s tons more easier hosting a few images compared to other media format like videos and music; there’s nothing to lose with selling DRM free copies. I don’t get why they bother with it.