It's not about if Metroid needs it, it's about selling more copies. And that's what Metroid truly needs.
Fire Emblem: Awakening and Fates are a good example of what the Metroid franchise could do to become more popular. So what if there would be a kissing scene with a girl near the end of a Metroid game? If it sells 300k extra copies who's going to complain? And yes, people are this shallow.