They advertise the app on every new expansion you buy, but honestly, I feel that they should offer the dice as a courtesy for buying their products. The app isn't necessary, and $5 is way steep for a dice rolling app.

I feel that FFG should include a discount or promotional code with new X-Wing expansions which lets you download the app for free. Any thoughts on this?

No its not needed...however you can also roll as many dice as you want on it instead of spending more and more on physical dice.