I definitely agree that finance is an exciting field where a lot of interesting topics converge. However, the examples you give are way exaggerated. The full complexity of the modern financial system isn't really needed to facilitate trade/provide insurance/provide financing/whatever else. Those things don't go away if fewer people are trading inside spreads.
Yes, liquidity is important for a market. But it's not an end in and of itself. There is no value in liquidity. There's only value in what liquidity enables. It's like what Paul Graham always talks about, you have to make something people want. Liquidity is kind of like ball bearings. No one really wants ball bearings, but they're useful because of what they enable. Liquidity is the same way.
Edit: I'm also not suggesting that there's no value in making ball bearings or intermediate products, just that they are not the ultimate goal.