I agree with the opinion that there's so much more potential to our current galaxy, so much more that can be done......but!
It amazes me every time when I'm out exploring that our whole galaxy, 400 billion stars, is working to a certain degree.
Planets are in moving orbit around their suns, suns move around eachother, moons are in obit around their planets and a lot of bodies rotate around their axis, and all this in real time.
When I'm trolling around on a moon by daylight, log off and come back a couple hours later, I find myself on the dark side all of a sudden.
To cool in my opinion.
Not seeing Novas or moons crashing is the least of things I miss, comets etc. or more stuff on planets/moons to discover and the tools to do so, that's what I miss.