I agree with most of the above criteria. Here are some comments I'd like to add. Of course, with reference to my name, I admit I might be biased towards the 767-400; here are my two cents on that regard nevertheless.
I understand there are limited livery choices for the 764, but the quantity and the quality of the existing releases are just as limited. There are NG moulds of which they are similarly obscure in terms of livery choices, and some even have active mould competitors; the 764 does not. Letting emotion get in the way of a major decision is indeed something to avoid, however I wouldn't say it is completely irrelevant in this case. There is still a reason that 'emotion' originates from.
I am in no way of trying to downplay historical significance, but I do have to mention that the last criteria inevitably puts emphasis on older aircraft types. Commercial aviation nowadays is more diverse, arguably more fast-paced, and we have a plethora of strong, well-known existing competitors that often hinder the significance of new aircraft. Besides, new aircraft such as the A220 simply has not been around for long enough to level the playing field. There is no doubt that historical significance is an integral element of collecting the retro era, but not so much for those collecting modern.
All in all this is indeed a very interesting topic of discussion and I'd love to hear more -- perhaps from NG themselves too since they are present in this forum.