Need in the sense that, it improves the quality of life, and it's a worthy expense.
Additionally in the very large houses the bed/bath ration doesn't capture the setting of the bathrooms. There is a house not to far from me that has a connected indoor pool and that has 3 bathrooms for changing/shower.
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These aren't small houses.
I have a very wealthy relative who lives in the USA, and I visited when my younger brother was just 6 years old. It took him several complete tries of running round the house to count all the bathrooms (and not lose count).
There was one per bedroom, then one on the ground floor, one by the garage and one which was easy to get to from the beach.
The neighbour's house's guest room's bathroom was also the general bathroom; it had two doors with appropriate locks. This seemed like an efficient design.