Just for a reminder of how bad it really was: at the end of the British Leyland body assembly line men with large hammers would whack the doors from below to make them close properly. Body panels were simply not made to the same standard that they are today and people didn't care that much about such stuff.
Not that your point about inherent complexity doesn't stand but having to whack body panels to make them fit just means the dies are at the end of their lives. They certainly would have fit without mechanical persuasion when the dies were new. The hood of any late 90s International S-series is a good example of this.
Note that it doesn’t really bother most people because while the defect rate is higher, the mechanics to fix those problems are cheaper as well.