Nuclear Option does, in my estimation, a good job of making simulation-paced modern air combat accessible for most folks.
In my time playing with others, I've found that the current missile envelope indicator can be a pain point for initiates or even more experienced players. At least one player (that didn't have a whole lot of experience) I know actively distrusted the indicator and frequently held onto their munitions even in situations where someone else might have found it acceptable to fire at their target.
I think there only being a single arc to indicate launch parameters when that's an aggregation of multiple pieces of data creates ambiguity for the player. An open arc could be due to range, aspect or degrees off bore. It's almost impossible to precisely measure how aircraft speed and altitude affect the weapons envelope, and I think those interactions are desirable to understand.
Lots of questions about the effective range of a motored weapon seem to come up as well.
Appropriate range and steering cues for air-to-air munitions would be nice bits of HUD symbology that not only communicate what kind of weapon the player has selected, but would also fill an information gap and take away guesswork involved in deciding when to shoot at a target.