Sure, the work doesn't change, just as a particular shade of red is exactly that shade whether it's in a sunset or an ambulance light. The interaction changes, but since the reader only experiences the interaction, the distinction isn't that important. (It's like that old Zen thing about it not being the flag or wind that moves, but the mind.)
If perfection comes into it at all, it's an attempt to obtain the perfect compromise. (Does that qualify as an oxymoron, or does it actually make sense?) Every novel tries to balance the many elements in difference ways, but the final result is static. The most the writer can do is try to remain true to their intention - whatever it is - and hope that the reader will follow.
And you're right, some novels reach beyond their static nature and transport the reader. There are some novels I could pick up in almost any mood, and they would carry me into their own. But reading reviews here on MR and elsewhere is a reminder that different people have different novels that do that for them. So what's perfect? It doesn't exist, there is only what seems best at the time.
I think that's an important thing for a writer acknowledge - if not before they start, at least before they get too far into redrafting. (Acknowledge, but not to use as an excuse to stifle the quest to "make good art" - as Neil Gaiman phrased it.)
The idea that a writer can never truly judge their own work is, I think, a curious paradox. A writer has no choice, they must judge their own work, they do that constantly as they write. Possibly the ability to step away from their work, to assess its merits with some accuracy, is something that marks the difference between a good writer and a bad one. Education, experience (reading and other), all contribute to a writer's ability to judge, while their closeness to the work impairs their objectivity, but the effect of that impairment is unpredictable. So perhaps "truly judge" is right, but it's also misleading since true judgement is hard to find (or even define).
I definitely do equate dissatisfaction with sadness. If I thought I could never be satisfied with my achievements then I would, as Zadie suggests, have to resign myself to a lifelong sadness - but I'd change hobbies/jobs before I did that.
You don't have to be dissatisfied with your prior efforts to also want to do better this time. I see the two as distinctly separate. Okay, so "the work isn't you", I accept that, but it is what you created as you were at a particular time, and it reflects that, and I think a writer needs to accept that rather than be dissatisfied with it. It is not dissatisfaction that drives me - I find obsession does the job adequately without any help
.
Long term and pervasive dissatisfaction can make a person unhappy with their life. I see this as something that leads to argument and divorce, and sometimes to depression and beyond. Many artists have had tragic lives (not that that makes them unique), and I wonder how often that is because of their dissatisfaction with a search for an unattainable perfection.