It’s also great for the animals too, since the more space there is, usually the more exhibit space the animals are given.
It would be very interesting to know whether this relationship actually holds true. In theory, a physically large zoo has an advantage to provide their inhabitants more space. However, in practice they may also house more and larger species and use more space for visitor facilities or "green space". It is not hard to find examples of appallingly small enclosures in large major zoos (until recently TP Berlin was a prime example) or generous enclosures with abundant space in even the smallest of zoos.