Coming in as a Mexican aristocrat, money has never been a problem for Alberto Del Rio’s character. He has always been well-presented, living the life of luxury which is represented every time he comes into the arena in a new expensive car.
Giving Rosa Mendes' expensive tastes that reduce Del Rio’s ability to spend money—plausibly leading to financial difficulties later in the angle—could open up a completely unseen side to Del Rio’s character.
Certainly, it would be the first time that Del Rio has been seen as truly vulnerable. Considering his aloofness during most of his run, it could reveal underlying insecurities that would round out his character, and help explain some of his motives.
There is even the possibility for this to explain some of his previous actions, like why he believed that being a great wrestler was in his destiny.
Certainly, any angle that explores Del Rio’s motives is a good thing for his future prospects.