I followed the run-up to the release NMS, never got around to buying it. RL interfered, amongst others.
The same can be said when ED was realeased, never purchased it then. However, a few months ago, came across FEII, and was introduced to ED again. This time I did bite, and 6 weeks later am having a ball. Yes, ED is not linear, has no "end game", and can be grindy at times (as much as you make it grindy that is, imho). The again, maybe it's just me, I had an Industrial char. in EVE Online, and loved it.
Can't comment on the X-series, never played them. SC, well, will look at it if it ever is released. But some others have already posted in this thread what I think ED is a niche game, it won't please the masses (but hopefully enough to continue development), but enough people are playing it. As others have said, ED is not a game for everyone. I have friends that I play other titles with, but won't bring them anywhere near ED. They would probably suicide their Sidewinder into the side of a station after the first mission.