I don't think the Nes was capable of pushing out the graphics from the arcade games. The 16 Bit consoles did a much better job at it. They did the same thing with other games like Mighty Final Fight and Ninja Gaiden which had completely different sprites or gameplay and still turned out to be a awesome games. Although D&D didn't have co-op I still feel they did a great job and it doesn't deserve to be treated as one of the worst arcade console port ever. The game is still a ton of fun to play, even if you can only play it by yourself. Have a few beers and take turns if co-op is such a big deal.
This is a interesting article.
http://www.d4gameplay.com/2015/05/8-bit-vs-16-bit-double-dragon-best-home-console-port/
I also don't think Final Fight for the Snes is the worst arcade console port ever, not even close, but when compared to other FF ports, it's one of the worst Final Fight ports that I played. They left out fuckin Guy, he's my favorite character in Final Fight, game feels incomplete without him, the sprites look funny and the game doesn't play as smooth as other Final Fight's. I think they could have done a much better job with the Snes port.
Final Fight CD, X68k Final Fight, Final Fight One GBA are still better ports of Final Fight.
Snes Cover
Sega Cd Cover
Nuff said.