They seem to have been caught off guard by the glowing. I’m guessing this is a result of Twilight’s resonance cascade, as opposed to their usual methods of ponying up.
(Basically they’re going by final boss rules. The universe is collapsing and you have to fight a giant demon, but on the plus side your super mode is automatically activated.)
EG magic seems to be triggered in a similar way. Being in close proximity to each other’s friends. Without a proper conduit, it’s possible it takes more effort to activate it. It’s also a possibility to have no conduit at all. Simply have a group of friends together, clap your hands or think happy thoughts, and the magic of friendship appears. This could potentially mean it doesn’t have to be the Mane Cast for magic to come forth. Just by being really good friends, BG humanoids could also use it. Which would signify the moment DHX incorporates the more accurate eared and tailed humanoids found in the EG toy line. X3
@atalarikt
I’d say it’s because there’s a growing influx of magic that’s destabilizing all of time and space, but that’s because I’m writing that story.