Even villains have a sense of etiquette.
It's an age old thing,.. hero seriously out-numbered by bad guy's henchmen?... not a problem, they'll attack one at a time!
You can’t just interrupt their transformation!
Honestly! You can’t just go interrupting people whenever you feel like it, and this villain knows it! Most villains these days don’t even have the decency to say 'Thank you' after mugging you! Those Magical Girl genre villains get it!