Many desire to never use the Windows Store out of either principle, a great many bugs that still exist, or both. Having the option to play without needing to go through the Store and the Xbox app is something that a lot of people want.
Personally, however, I don't believe that the game will somehow die without the Arc client version. So far, it seems the Xbox crowd itself is enough to sustain the game for the foreseeable future. And who knows, maybe when people get a whiff of the game's active, slowly growing population, they'll begin to contemplate trying it out regardless of the means to get the game.
