This feature is still there. in 1.4 you only had the DnD interface, and if you select a DnD project in 2.0, you'll still be able to do this.
The GML only project settings is a new feature, and you can only have 1 script per event in this mode - otherwise you'd have to continually drag and drop script blocks into an event list again, making it basically still DnD mode.