Yes but the return on investment in a new, innovative plane would have been well worth the wait! Now look where they’re at and all they stand to lose! Regarding Airbus A321 - from my understanding, the foundational structure does not present the same aerodynamic/gravitational challenges as the Boeing 737 — when it comes to things like placement of the new engine on the plane, how far high it is off the ground, etc...
I just posted US Army’s frustration with Boeing among others:
https://breakingdefense.com/2019/04/army-tells-shoddy-suppliers-shape-up/
Just to be balanced and fair why don’t you research Lion Air and Ethiopian Airlines to see how bad they are?