Well it is laziness. They have always managed to keep specs separate and unique before now even with similar elements. Oh yeah cause purple skin unique player picked tattoos the wings/horns looking different. But it's totally a clash of "different themes". It's like you're saying "It's okay they could delete every class but demon hunter and I wouldn't care." It's not right that they just decide to service some fans who stopped playing as a money grab (yes thats what legion is going to be) and completely drop a very lore rich classes lore. They can do things so easily. I don't get how you don't see that. Paladins get wings by your definition thats a clash of themes with demon hunters. Even though they look different and act differently. Right?
I mean come on. They are basically going "Our players are idiots and wouldn't understand if these things are even slightly look alike" which they aren't even close. Demonology warlocks wings look 100000000000000000% better than the crappy wings that demon hunters are going to have. The horns could be different too quite easily. Or are you telling me that on legion release if I walked around with felheart horns and jumped made wings proc everyone would go "OMG DEMON HUNTER COOL!"