Such are the dictates of the fashion world. Practicality has little to do with it.
Womens clothes are always a case of “Form over function”.
Case in point: the enormous numbers of women suffering from foot deformities, back problems, joint problems from a lifetime of teeter-tottering around in high heels simply because men like how they look. Form over function indeed.
If they made womens jeans with larger pockets, they wouldn’t sell enough to make a profit. Plain and simple.
A few of us on this Q might buy them but not a whole lot more in the real world. Most women would far rather be inconvenienced with small pockets than to look lumpy.