This is incorrect, majority of the destiny player base doesn't even play the game anymore or they never finish it and most games are like this where people rarely even finish the game. If we are talking about active player base then I have a hard time believing that most of those don't play raid...anyone who plays destiny regularly has friends who play the game.
And I don't want to play a horde mode, I hate playing horde mode because all you do is sit in one area and kill waves after waves of enemies. The only variation of it that I've ever liked is Zombie mode. Thing is there is no sense of progression in horde mode, raid feels like you embark on an adventure regardless of how many times you play it...there's an end purpose to all of it. Horde is just plain boring to me.
But the main question is, why is Arena considered to be a replacement ? Why can't it be supplementary to the raid. I know why Bungie isn't releasing a raid because they haven't finished it most probably and why they haven't finished it is a different discussion, but this question is towards the people who are saying things like what you just said that "maybe they wanted to make things easier".