Anyone who thinks Elite has grown a lot in that time needs to go and look at the wider market. Go and look at Warframe, with its constant stream of free updates full of major new features.
Yes, Warframe, a game that has been out for two and a half years, had very little content at launch, and is funded by a pay-to-win-faster model. Personally, I would be very unhappy if FD started selling packs in the store that gave players X cr, or a timed percent boost to trade profits, or whatever.
I understand what you're saying about Elite's emptiness. I agree on many points. I think interactions with NPCs need improvements, since this is not a multiplayer game in the same sense as EVE or WoW. We need more and better basic missions. I think a lot of small things in the core game need improvement - not massive overhauls, just fixes. But the vastness is something that actually draws me to this game. As a great man once said, space is big. Really big. And I love the fact that I can cruise around in a 1:1 model of it. It's never going to be as densely populated as GTA or Skyrim, but I personally don't want it to be. If I walk across a fantasy countryside, I expect to run across all manner of wanderers and monsters and ruins and whatnot. When I fly through deep space, I expect to find... nothing. If and when I want my Hollywood-style space fix, I'll go see if Star Citizen has been released.
In short, I think Horizons sounds like a step in the right direction in terms offilling in ED's largely blank canvas. I really hope that FD improves the core mission gameplay, because that is a sticking point for me as well. But I don't think FD has been sitting on its collective butt for the last eight months adding nothing to the game.