As I've already said, one of the most important elements for enjoying any MMO is having people to play with; this requirement is (in my opinion) an absolutely unavoidable consideration for long-term enjoyment. EvE is no exception.
What's different about EvE is that one of the ways players choose to play with others is by blowing them up, which (again, my opinion) makes EvE a lot more like 'normal' games (Chess, Monopoly, Clue, Cribbage, et cetera) than a typical MMO, because a lot of the fun you're having comes from pitting yourselves directly against other people.
In fact, if you can find other people to pit yourself against, that's really all you need; there's no 'raid gear' requirement or level-cap. Aside from being vastly outnumbered or outgunned, if you can find an opponent, the rest boils down to -- in the words of Fezzik -- "skill against skill alone."
[Fezzik demonstrates what it's like to fight a frigate while piloting a battleship. Fezzik needs a small drone bay.]
Consider: once a player-versus-player game is sufficiently honed, balanced, and functional, it doesn't require regular infusions of content to remain interesting and entertaining. Witness: Go. Diplomacy. Risk. By contrast, MMO's require constant content infusion; a fact which is changing the gaming industry as a whole (even those parts unrelated to MMOs) into a Ongoing Service industry.
Anyway, in EvE, we have a situation where conflict with (or the potential for conflict with) other players can be a powerful fulcrum that allows the creation of a lot of 'stuff to do' with very little effort (by the developers) once all the pieces are created and functioning properly; the content comes from the other people playing.
(Which not to say that EvE is functioning with the flawless balance of a Go board, though perhaps parts of it are. Witness wormholes, which were introduced in EvE 35 months ago (read: 90 years in internet time) and have since, in terms of code and content, remained virtually untouched by developers, yet continue to pull in more players every day through the powerful attractive force generated by providing self-sustaining and well-designed tools for personal agency. More on that agency in a later post.)
It's also the reason why the most recent Crucible expansion got EvE players so excited, even though (by a typical MMO's definition of the term) there was no (or very little) new content (read: new "stuff to do"). Almost the entire expansion consisted of Quality of Life improvements and bug fixes -- it was a honing of EvE's version of the Go board, and it thrilled the player base simply because it would let them play the game they already loved, better.
What do you get an avid Go player who already has a board and pieces?
A nicer board with higher quality pieces.