That the laziest of us don't mind and the worst of us want something is not a respectable argument for anything, ever.
We can have a discussion about FaceID specifically, but “convenience” is not considered trivial within the security sphere.
Second, I work for a (very large) bank, and you actually do not want to trust them with your biometric data directly. You can be absolutely assured of the privacy of your biometric data with the bank, better than with a Silicon Valley tech company. But I would not trust the bank’s data scientists to come up with a model that will not have an extremely high rate of false positives and negatives.
The reality is, if such an initiative was started at a bank, it would be shuttered after years of delays.