Allow variable instances of symbols (or imported ai)
I feel that the reason so many UI projects go Sketch instead of Illustrator is due to componentization of elements throughout the document in collaborative environments.
I feel that Illustrator has much more power and could be used the same way, if only a few features were added.
One of the most important is allowing the use of symbols as UI elements by enabling variable fields.
Currently, I could make a component and save it as a symbol - but if I was to use it in multiple places, then I would need certain fields to be altered.