I want to put my opinion out here on this "depth" subject.
First, I'm well north of 60, and not currently playing Elite, but I am considering picking up the game, so I thought I'd check some forums and see what's what, do some research, and I see there's quite the range of opinions on the game.
I played the original back in the mid 80's, on a green monochrome screen powered by a Apple II with a massive 640kb of memory. I don't even think "gigabyte" as a word even existed back then, let alone "terabyte". The game was amazing then, stuff you'd never seen, or even imagined. I spent hours and hours and hours trading, flying combat missions, coming to the aid of traders and stations, increasing my rep with factions, discovering mysteries which seemed to have no clues while exploring, (ah, but they were there, if you looked). Found myself (more than once), in a system with no scoopable star and outta "gas", (no fuel rats back then either). Gambled on one big score without insurance only to see my plans land me broke, and starting over on some dump of a station. I'm struck by how much of 84's game is still there in today's game. While "primitive" compared to today's version the learning curve was even steeper then, you have remember nothing like Elite had ever existed, a computer "video" game was text based, and how to play such a game(?), the "rules" were pretty much nonexistent, the "story" was what you made it, the "narrative" was your own.
Games have "improved" since then, now there are "deep, wide arcing narratives", "engaging characters" "immersive locations" and "cutting edge" graphics, and all sorts of other wondrous adjectives. Many gamers of today never saw those early days, they have seen video games evolve from "graphics masterpieces" (compared to the the beginning games such as Elite) to near photorealistic worlds. Those games have grown, and evolved to coin all those wondrous adjectives above, and become, not features, but expectations of any game, not just Elite, to today's gamer, so I can see why they are saying what they are. Really, there's no "right" answer to these questions, depth is where you find it, taste is individual, and often acquired through different circumstances, one players belief is just as valid as anothers.
For me, in 1984/5 Elite was "lighting in a bottle", and I'm thankful I got to experience it, and from what I've seen and read, for me at least, that "bottle" seems to have a little charge left, who knows maybe I'll see some of you in the black, fly safe Commander's o7