Myrna Loy wasted in this role, imo

Of course, a woman can be lovely, independent and intelligent and still be a "wife"! (In both real life and "reel" life.) But you're right, she did get shunted into "wife" roles, although her wives were seldom just innocuous types -- even as Nora Charles, and in her roles opposite Grant, she was certainly a feisty, independent, intelligent female, the equal of her leading men. Actually, being typecast as the "perfect wife" might have been a welcome change for Miss Loy, who in her early career was typecast as "Oriental villainesses" and the like, mysterious, evil and usually under-clothed temptresses from exotic places.

One drawback to Cheaper is that although we're told she's a psychologist and engineer in her own right, nothing is ever made of it. We see her helping her husband maybe once in the film, but the rest of her time is spent simply being a mother -- which, admittedly, was something she couldn't entirely escape, with 12 kids. Her decision at the end to carry on her husband's work therefore comes a little out of nowhere, because she hasn't been seen as being that involved in it at all, as the real Lillian Gilbreth apparently was. The closing narration indicates she achieved her professional goals later in life, but again this is almost an afterthought. Interestingly, in the sequel, Belles on Their Toes, based on a follow-up book by the same two Gilbreth offspring, Myrna is shown fighting battles for equality and professional recognition against a male-dominated establishment, and prevailing. Though not as good a film overall as the original (someone at Fox had the bright idea of inserting idiotic and unrealistic musical numbers every so often), in its basic plot Belles is something of an early clarion call for feminism, and Myrna's character is much more fleshed out and dominant than in the first film.

One final surprising thing: in a career that spanned almost six decades, and with several excellent performances in such varied films as The Thin Man, The Best Years of Our Lives and From the Terrace, among others, Myrna Loy was not once, ever, nominated for an Academy Award. Luckily, the Academy finally, and in the nick of time (or nora of time), got around to presenting her with an honorary lifetime Oscar just a couple of years before her death. An astonishing oversight, all those years.