volatiles - from which biological material is constructed - not in a
deep gravity well, such as is found on the gas giants.

It is true that there are also Io and Europa, for example, but
radiation may be a problem with them, or other concerns, even
aesthetic ones, may be operable.

What is so nonaesthetic about the Jupiter system? It's not Saturn, but if (big
if) you could live on I&E without being cooked, Jupiter's proximity might be
the penultimate travel-photo op in Sol system