- the need to install something explicitly (separate from the app)
- the need to name them "widgets" (to the user they're just a fancier icon), which reduces the apparent complexity to the user
- they are completely invisible unless invoked by the user, thus preserving the simplicity iOS
- they have a natural and fixed size that helps preserve the visual aesthetic of the grid layout, without special efforts by the user
...and probably more - that's just off the top of my head.
I don't know if they're a good idea, by the way. But it's not good to just dismiss them as "android widgets".