Honestly, in Precure and Sentai alike, the transformation sequences are implied to be instantaneous in-series. They're there as stock footage- which allows them to save on production, pad out the show, and in more extreme cases, shoehorn in creepy fanservice.
Though if you want to go with "logical" reasons magical girls are never attacked:
http://brickme.tumblr.com/post...er-attacked-during-a
Now we are in my ballpark- my technicolor spandex ballpark. In Sentai, there's various energy constructs that form the suits: ranging from angry dinosaur ghosts to full-sized trains to magic electricity to the literal hands of God. In Pirate Sentai Gokaiger, we see a bunch of Sentai heroes decades after the fact. OhRed is still hardcore, Doggie's able to arrest the new Red Ranger for space piracy, the MagiRangers are still wizards, and the dinosaur teams still have their prehistoric killer robots. Basically? All they lost, over 10-40 years of not fighting, was the suits and fireworks, which they gave up to drive off an evil alien empire.
The shows have covered these tropes since day 1. If anything, those traditions are in place to protect the MONSTERS.
But yeah, I've wanted to do something toku and/or magical girl based for a while if people are still interested.
This message was last edited by the user at 00:31, Sun 01 Nov 2015.