I would suspect the comments about "easy to restore with minimal parts" might relate to the quality and durability of the interior items involved. Not that they didn't deteriorate, but it was apparently a slower process because they started at a higher level than other similar cars.
In the '80s, I'd take a vacation day and head to a local salvage yard. One day, I was sitting inside a '67 or so Chrysler and admiring the shininess of the interior chrome AND the un-cracked instrument panel pad. Definitely better durability than what GM had back then, by observation. So, even on their normal models, Chrysler was using better materials which held up better as the cars aged.
Mechanically, there probably was not much difference between a normal Chrysler and Imperial. Except that a lot of the Imperial's electric doo-dads were probably designed back in the middle 1950s (for the 1957 introduction) and might not have received periodic updates for better operation? Just a suspicion.
The Auto-Pilot was a Dana/Perfect Circle sourced item, as I recall. Not as easy to use as the later 1960s units, I suspect.
The electronic headlight options were probably right out of the Delco-Guide parts bins. Which means Chrysler switches and parts ID on otherwise Cadillac-use equipment. Funny thing has seemed to be that a Cadillac owner might have similar issues with some things as a Chrysler or Imperial owner might, but the GM owners tend to be more forgiving of the components than a similar Chrysler owner might? Considering how many flubs that GM divisions tended to have and the owners kept right on buying GM cars. Sure, a GM owner might bad-mouth their vehicle and its problems, but next time around, they are right back at the same dealer for a similar car (possibly without the troublesome options).
I can kind of understand the "have to know how to use them" orientation, but I also suspect that few dealer operatives had real knowledge and experience with these things. Meaning, outside of the owner's manual section on how to operate those items, the customer was on their own for their own education of "how to use them". Here they'd spent a chunk of chnage on these new luxury car options to make their driving easier to do and NOBODY could really help them figure it all out! Not good.
Auto Pilot was probably at its best on the new Interstate Highway system where a constant speed was possible for hours on end. The headlight options might have been difficult to adjust and such (as mentioned). End result, those options were not really as beneficial as they might have been, for many customers. Who decided they could do things on their own and do it better.
Which tends to put things right back into the lap of the selling/servicing dealer and how they responded to the concerns of dissatisfied customer. Which has tended to be, by my own observations, a weak point of the Chrysler dealer body over the years. They do well with existing customers (whom they have developed a good relationship with), but with a new customer with many expectations, things usually don't go quite so well. Also, it seems that long-time Chrysler dealers, even with a family succession plan, did better than "newer" Chrysler dealers did. Perhaps GM dealer employees were used to seeing mad customers and better knew how to deal with them?
When the pre-'67 Imperials were new was when I was in elementary school and junior high. I knew they were special cars owned by special people. I liked the '64-'66 Imperials the best. Stately style and elegance PLUS they knew what to do with corners and rough roads. Only thing which came close, to me, were the Lincolns (in style and elegance).
Here's ONE thing that, no mater how good the Imperials might have been . . . I overheard a sales rep say that he always drove Cadillacs, but decided to try a Lincoln one time, as he traded every year or so. All of his friends recognized him in a Cadillac, as they waved at him and he waved back. Then he got a new Lincoln and suddenly his friends were not waving at him, although he waved at them. He asked them why they never waved anymore? They responded "We didn't know that was you (in that Lincoln)." So, next trade cycle, he got another Cadillac and everybody was waving at him again. That tended to explain the many repeat Cadillac customers as it was obvious to me that Cadillacs were certainly NOT "The Standard of the World" by that time (earlier 1980s). The sales rep admitted that the Lincoln was a better car, but he had to drive something that people expected him to drive, so he kept with his Cadillacs.
Observations and thoughts,
CBODY67