I don't get it. It's not as if walking around with a first-person view ground-breaking in the video game industry. I would have thought by 2018 most developers would be able to do it quite easily.
It's simple.
Right now most of what you see in the verse is 2d.
It might LOOK 3d, but in reality apart from collision boxes, it's all just 2d representations, they have no "depth" - they are all empty boxes.
Spacelegs would require that all those things you can see, that can be interacted with, be made whole - having an "inside" that corresponds to the visual you see outside.
To be done to any degree that players would resonably accept - all small ground based structures would have to be built from the inside out - all space stations would have to have a resonable amount of explorable areas, and far more than just the landing pad and a trading post.
Larger ground based structures such as MIGHT arrive IF atmospheric landings ever appears would also need a good sized area to walk around in.
All of those assets takes a considerable amount of time, skill and more importantly resources to develop.
Anyone who's familiar with SC's dev diaries regarding this would understand why I doubt FDev will ever produce anything significant to make "space legs" anything other than a very basic experience.
I've said elsewhere I doubt they would do much more than allow you to leave your ship, but only have the landing pad and a trading post area to walk around, and all of the rest of the enourmous space stations remain completely off limits.