You've hit the nail on the head there. It's a sort of suspension of disbelief/taste thing and you're either in or you're out.
I am the opposite of you in that the nostalgia kicked in first and made me predisposed to a decent score, however I am very conscious if I continue with my listens then I will start picking at the threads and it will end badly. I had already started to muse on the mystery of David Essex's spoken voice career (entirely understandable when accompanied by the pretty boy visuals of things like That'll be the Day and Stardust but shorn of that, quite mystifying). Or the fact that whatever the concept of 'Total War' should sound like it certainly isn't this (other than arguably Burton's narration itself).
So, because I don't want that to be the outcome I have decided to do something I've never done on here before and have stopped listening before my minimum three, in order to 'preserve' my score. It's intellectually dishonest (and yes I am aware that applying that term to a football forum music thread makes me even more pompous than this record) but it's also how I feel and the emotional generally trumps the rational.
One specific thing on your comment about the sounds used for the aliens, whilst at one level I agree about the lack of metallic clanging I think you need to take into account the context of the era. Synths were still fairly new, though apparently Wayne had had a Moog since the late 60's, and the sci-fi/space sound aesthetic of the day I think was more cosmological whooshing than steampunk/industrial clanging. Not withstanding that, he did apparently uses his missus's pans to create some of the sound effects; though I suppose they could have been some of those fancy ceramic ones in which case your point would still stand.