I don't know if we should just write it off as it "being the '80s" but the way that Margot Kidder and Mariel Hemingway's outfits in this movie look are for the most part, really garish, unflattering (what was with women back in the day and shoulder pads) and tacky (especially when Lois and Lacy go on that "double date" with Superman and Clark) looking.
shareIt's been a looong time since I've seen this film, but I do remember that even back in the day when shoulder pads were fashionable, both of them were terribly costumed.
I remember that Lois wire all pink and white, as if the costumer was trying to make her look like the good girl to Hemingway's vamp. If I'm right it shows the costumer designer didn't understand Lois at all, she's not a good girl she's a tough broad.
Pink didn't suit Lois. Like you say, she's a tough broad. She's not the girly-girl (if anything Lacy is more the naïve, innocent girly-girl, albeit one with a sexually predatory side towards Clark, which, I must confess, I find rather hot).
Lois' costumes were terrible, but the character had already been sadly diluted and marginalised by that point (following the stand Margot Kidder, and others, took after the Salkinds had fired Richard Donner on the set of Superman II). However, I think Mariel Hemingway managed to make her sparkly lamé dresses work, especially when she is trying to seduce Clark. Admittedly, her spoiled little rich girl using the job daddy has given her to sexually harass the staff, isn't a very pro-feminist concept (and would have seemed less egregious if she'd been better counterbalanced by a feistier Lois who actually had something to do), but at least Hemingway, to her credit, endows her with a certain sweetness and underlying decency, so she's not just a vampy bimbo.