Well, I believe the issue here is not to make things realistic but how realistic they should be compared to our "reality". What is the threshold, the limit?
That being said, I find quite interesting the idea of not landing on the Gas Giant themselves, but on their Moons. If their environment is similar to the reported by NASA/ESA/etc., imagine how many kids could "learn" about the Sol System, and not only their planets but their moons too, some of which could be very fascinating. I don't know how is Basic Education (Elementary, High School) on your countries, but at least on mine, they usually neglect to give any importance to the moons of the planets, only to the planets themselves. I've found already many articles that relate Minecraft not only for the entertainment of the elders but also as a tool for the kids to learn about stuff in general, despite not everything being so "realistic" for game/fun purposes.
If the modder wishes to take some time, the moons could even have a "view" to the gas-based planet itself, just like the Moon and the Earth.
Maybe there should be a poll or something, as long as the developers are willing to hear our suggestions on this particular field, of course.