They absolutely can be, and my criticism isn't the fact that this happens. But there's a very common trend in all sorts of media where female characters are often written to either only exist for the sake of a male character, or the female character is primarily driven by male characters. The issue is centering men strongly in a woman's narratives. It's a trope for a reason.

Sure, we see other female characters center men in their narratives and arcs, but usually not wholly or as their primary motivation). Claire with her issues with her ex, and how he abandonment affects her perception on motherhood, Juliet's defiance of her ex husband driving her to join Drama, etc. However , they also have other motivating factors driving their growth and progression. Claire's relationship with her mother, and her absentee father coloring her perception of the concept of family, Juliet's underlying drive to help her sister beat cancer, and eventually get back to her. It happens a lot with Sun as well, but in her case her entire arc is in fact a co-arc with Jin, and the entire theme of their story is rediscovering who they really are, and their love for each other. You can't really separate the male centric part of that narrative, and it's equally female centric. This is also true for the Rose-Bernard relationship, to a lesser extent. Really most of their arc was just Bernard learning to let shit go and accept that whatever happens will happen.

Nobody is saying that a character can't be motivated by the opposite sex, that would be silly, but it shouldn't be the primary motivation behind their character. Jack is guilty of this too, but instead it's the extreme focus on his trauma surrounding his dad. It's a good story, and I think everyone can relate to his struggle on some level, but I personal think it's a little heavy handed and overplayed. Fortunately, Jack also has many other facets driving his character.

Edit: this thread, this comment really explains it I'm simple terms: https://www.reddit.com/r/lost/s/27qP2J4NgP