No, the question of 'why is there a big city here' is a super legitimate one. Cities aren't their own justification. Trade doesn't happen because it's more fun to move stuff long distances than not. Cities need serious flows of goods coming in to exist, and some way to make those flows happen. In many cases on Earth those flows are geographically or governmentally determined - neither of which seems possible for Neon.
(And a luxury tourism city is in many ways worse because that only works if you have enough mobile luxury-seeking elites coming through to support a city. That's not a minor thing.)
Okay, let me try to twist this from iron bar for you.
1) Neon is founded as simple fishing rig. Seeing how it's far away from everything, naturally it develops into company town, where people are born, work and die. People don't commute from other star systems, they are going to live on the rig. So businesses catering to fishery workers forms.
2) Aurora is discovered. Since this is the
only source of it, it quickly becomes a very profitable business. Night clubs are founded where Aurora can be
legally enjoyed. If you want to imagine this in real life, imagine that a nation designated a single city as "pot capital", place where marijuana is legal. I trust you can imagine business that would very quickly grow there.
3) With tourism as increasing business, Bayou creates Trade Tower to invite other corporations in, promising them freedom from regulations. Considering that, at the time, your option was UC or bust, a lot of corporations pick this option. Most notably, Ruyjin who go so far as to build Ruyjin Tower to serve as their conglomerate HQ.
4) With corporations moving to Neon, their employees follow them. Once again,
people are not going to commute from other star system. So businesses catering to
those people arrive to make money. GalBank follows the follow. Terrabrew brings not!coffee to all those office workers. You get general store people. With not only corporate sector booming, you also have Aurora fueled tourist economy where people come all across the Settled Systems to enjoy some legal drugs.
5) Again,
people won't be commuting from other star systems for work for fucks sake
Is this too complicated? Do I need to simplify it further? Drugs make money. That simple enough?