This is my opinion
There are good sides and bad sides to this:
Good sides: Slower maps that most people cannot stand will be faster, and more fun to play. Also it gives us more of a challenge for the normal, hard, and insane maps.
Bad Sides: For people who DON'T like Nightcore or the speed have to turn off DoubleSpeed for everysingle map, and for certain maps that are already fast there's no point in making them faster, it'd be almost impossible for most people to be able to play.
To be blunt, I don't think making DoubleSpeed automatic was the best choice. Don't get me wrong, I LOVE Nightcore, just, not to the point I want all my maps to be Nightcore-ified.
If you guys ARE going to keep it this way, then at least make it an OPTION for people to want it in Nightcore mode, so that way people can just switch it off instead of having to go to the Mods and turn off DoubleSpeed for EVERY SINGLE MAP.