Cool video demonstrating a concept for easier granular control of the cursor: swipe left or right across the keyboard to move the cursor respectively, and more.
The tap-and-hold bubble is neat but can be very frustrating and slow at times, especially when trying to fix one letter. In fact, a not-insignificant reason to use a Bluetooth keyboard when doing a lot of typing on the iPad is for easier eding of the text. It’s why all these iOS text-editing apps (Byword, iA Writer, Writing Kit, et al.) have dedicated cursor mover buttons.