I guess I fail to see the problem with this Proposal. No proposed artwork changes. No proposed skill changes. No proposed game play balance changes. Basically, there is no functional change at all proposed here aside from being able to ride an already established creature. I support this idea wholeheartedly. Role playing guilds would absolutely love changes like this. The purists will shoot down any change, but at the end of the day...there's no impact to the gameplay on the server. It doesn't change any advantages/disadvantages. It essentially does nothing but lend variety to the game.
My yes vote is predicated on there being some requirement. New mounts for accomplishing some VERY difficult quest or through multi faceted reward accomplishments (Plat plus vet reward plus taking an eye-from-stick-poke) lore
The dark steed back in the day was confused for being a nightmare all the time. It had the same "pure" hue as a long maned nightmare but it used the same horse type (the one with the short mane) as the silver steed: http://www.uorenaissance.com/info/?page=g_info_t5&id=1047 There was a thread on Second Age a few years ago where someone was claiming that a nightmare shade was supposedly missing. That wasn't exactly true. The screen shot that the original poster pulled up on this thread was a dark steed, not a nightmare: http://forums.uosecondage.com/viewtopic.php?f=8&t=23435 I probably had one of the last remaining dark steeds on Lake Superior before I lost it after losing my connection and it looked exactly like that. I believe that all the nightmares here currently use the same hues as the ones that you would find on the official shards.
the ONLY thing I think would be cool is a white mare.... or unicorn whatever... hell even if it was for only females i'd go make a female tamer