Extracting profit by performing a service (in this case sub-millisecond trading) for the owners of the funds / banks isn't only important, I'd say it's perfectly moral. So long as your not cheating, and everyone knows the rules.
Yes, but patently not important to bitcoin or the bitcoin denominated market. It's potentially detrimental, in fact, to bitcoin and the bitcoin denominated market.
The science is impressive, of course, but that's not a reason to advocate the use of it here.
Obviously if bitcoin gains significant traction and the attention of big funds and banks, HFT (and other financial wizardry) in the bitcoin denominated market is inevitable (unless, perhaps, HFT is banned or otherwise hobbled in the real world - not totally beyond the pale if you consider the market dips and crashes already attributed to HFT).