poor British military. poor future where they dictate fashion.
as all of it is just my humble opinion and offtopic, i'll hide it and will stop discussing it.
No, an opinion is fine. But I've always felt the Nostromo flight suits looked entirely real and practical, and don't call attention to themselves as fashion (although it certainly was a costuming decision). Indeed, look at the standard flight suits NASA uses - entirely practical and banal:
I think
Alien very much respects the practicalities of flight and space travel in the Nostromo designs, as these 'space truckers' would need functional wear that would respond to work conditions, etc. There's discussion elsewhere of how the suits, labels and insignias perpetuate corporate conformity, but it's also a clever design (and characterisation) decision to allow the Nostromo crew to nevertheless personalise their costumes - Brett's cap and shirt, Parker's head band (which can also be used in a functional manner befitting a mechanic), Lambert's cowboy heels, etc.
The beard that Dallas wears is also notable: one could suggest it's a throwback to the historically cliched image of a 'captain of the ship', but in the context of
Alien it's also interesting in that Dallas wears that beard
into hypersleep. The Foster novelisation of
Alien remarks upon that, and it's a clever little character point, as although Dallas commands respect conventionally he's not above making a personal choice above accepted protocols (i.e. irrespective of military/company grooming standards, would it be wise to grow a beard in hypersleep for up to years at a time?).