There is a client hardware budget limitation they work towards, they talked about this in the last Calling All Devs, the difference between what they would like to do and the reality of what the hardware can reasonably render.
Having said that CIG are different to most game developers in that most game developers aim for consoles, CIG are making a desktop exclusive game where the hardware is much more powerful, So Star Citizen will never run on an Nvidia 1050TI, even with the lowest settings, but at a minimum it will run on a GTX 1070 or even a 6GB GTX 1060, that's a mid range GPU from 2016, i don't think that is unreasonable.
Its also ever evolving, it looks very different today vs how it looks now, it is also a live test environment, they are testing the limits of what they can do graphically, as an example the planet tech is on its 3'rd major face lift, the overall graphical quality is improved little by little from patch to patch to patch.... some time its hardly even noticeable, but it is there.
This is what it looked like in 2016, its Port Olisar, that's the Gas Giant Crusader and the ship is the Agis Gladius. i liked the way it looked and sounded back then, it had a certain charm to it.
Source: https://www.youtube.com/watch?v=NJ2hm09NHho