Sanji & Nami vs Kalifa made sense because there was a clear reason why Kalifa had to be defeated. Sanji may have lost to Kalifa, but at least he tried to take her key.
The payoff for Nami vs Kalifa was three-fold. Nami fought Kalifa long enough for Chopper to take Kalifa’s bathtub and use it to save Sanji’s life. Nami was able to defeat Kalifa, protecting Nami’s crew mates from both of Kalifa’s hax abilities, Relaxing and Golden Bubbles. Nami was also able to get Kalifa’s key and use it to save Zoro’s life.
Sanji & Robin vs Maria was a case of Sanji putting himself in danger for no reason. Kaido ordered Maria not to join the war and instead to hunt down Robin. Sanji was distracted from his priority of helping Luffy, he was tricked by Sarahebi, and was easily captured by Black Maria. By doing so, Sanji made himself a hostage and almost lured Robin into the same trap.
The payoff for Robin vs Maria was simply Maria’s defeat. Maria needed to capture Robin alive, and Robin was simply defending herself. There were no additional benefits that came with Maria’s defeat, beyond Robin barely surviving. Likewise, Wanyudo and Maria’s spider web hax were easily countered by Brook’s Soul Solid. If Robin had lost to Maria Brook would have finished the job.