I only wish the TIE wings collapsed like that, it’s a great concept.
Looking at these and especially the “Art of Force Awakens” book, I really got the feeling that they were constrained by time and budget by what they put on screen. Don’t get me wrong, it’s a terrific, fun, epic movie, but there’s lots of things in the concept art that would’ve been pricey to put on screen… like lots of crowded street scenes, big cities, and new ship concepts.