1. Cosmo's Sacrifice: Cosmo's tragic fate, sacrificing herself to save the universe, creates a deep sense of melancholy and finality. A romantic relationship, especially one that ended in such a way, leaves a bittersweet taste and could detract from the emotional weight of her sacrifice.
2. Unrequited Love: While Tails harbored feelings for Cosmo, she never explicitly reciprocated those feelings. Focusing on their love story would imply a level of romantic interest from Cosmo that wasn't truly present in the series.
3. Different Priorities: Cosmo was a warrior with a strong sense of duty and responsibility. She saw her relationship with Tails as a friendship, and her primary focus was on protecting her planet and the universe. Introducing a romantic element would complicate her character and potentially diminish her selflessness.
4. Potential for Fanfiction: Many fans prefer to explore the potential of Tails and Cosmo's relationship in a fanfiction setting, where they can explore the dynamics and complexities of their connection without the constraints of the original series.
5. Lack of Development: Their relationship, while touching, was largely underdeveloped. The focus was on their friendship and Cosmo's sacrifice, not a romantic connection.
Overall, while Tails and Cosmo shared a special bond, their relationship in Sonic X wasn't developed enough to support a full-blown romance. The series focused on their shared mission and Cosmo's tragic fate, leaving fans to imagine what could have been.
Ultimately, whether or not this pairing "works" is subjective. Some fans find it a beautiful and tragic love story, while others believe it detracts from the series' emotional impact.