Futurology

The best place in the universe for radio astronomy is on the surface of the far side of the moon. It's the only spot that's 100% guaranteed to never get directly hit by terrestrial radio.

Optical telescopes... probably one of the Lagrange points. But on a space station is ok too. Just too easy for the station to cause vibrations and out-gassing to interfere.

I'm not sure about using it for interplanetary gateway. It feels like it's not the best place, but I'm just some knucklehead that's played too much kerbal. I think having an earth orbit refueling station, or a lunar surface refueling station would be more useful.

That being said, I wouldn't complain if they did any of those with the gateway. Just feels like micro-gravity and radiation research are the only real things that can only be done on a station to this uneducated citizen.