I do wonder if early world explorers had been from the southern hemisphere and a tradition of "south up" was already established, if it would still look better to us to have more land on top.
No, the preference is conventional.
I should note, though, that Chinese maps were traditionally south-up. There's no reason to expect what hemisphere people are from to control that decision.
(Not only did the Chinese come from the northern hemisphere - they had an official orthodoxy holding that the north of China, where they originated, was morally superior to the south!
Nevertheless, they drew their maps with south at the top and referred to compasses as "south-pointing needles".)
The southern hemisphere historically navigated using wave patterns and stars with maps made of sticks and stones. So I expect they have different navigational conventions. I have heard of an southern hemisphere island that provided on their navigational orientation based on a mountain top.
The pole star could also be part of this convention. The pole star appearing in a consistent point may also contribute to this standard.
Though it appears we don't have any cities.