They're the kind of game that it's very, very satisfying to master. There's a real learning curve, you have the sense that you're actually learning to fly a spaceship and getting better at it. Missions are a true challenge until you've mastered them. And they're much more elaborate and almost set up like a puzzle compared to a Wing Commander patrol.
True. The trouble with that approach, however, was that you wind up with a kind of double learning curve. You're learning to fly a spaceship and getting better at it. But for every mission, there is a completely separate learning curve. With many of the toughest missions, you find that your skill with the spaceship is fundamentally irrelevant; it still comes down to you learning the details of the mission, repeating it until you know exactly when the different scripted events happen. You still need the spaceship mastery, but that's just the start.
I think this was ultimately an inferior gameplay model, because it made for a game where your learning curve frustrations are not ultimately rewarded with replay value. You can go back and replay Wing Commander again and again, even after many years. Going back to X-Wing, especially if significant amounts of time have passed, is far harder to suffer, because you find that while you can quickly recover your spaceship flying skills, the missions themselves are inscrutable puzzles yet again having to be solved. At which point, some people go - "yes! This is as hard as I recall, it's great!"... while most people just go, "eh, I did this once, no point torturing myself again."
Heck, X-Wing doesn't only lack replay value due to this choice, it also lacks basic enjoyability. Due to many disruptions, in some cases lasting for years, it took me more than a decade since X-Wing's original release to complete the game. Then I started the expansion pack. Again, something happened that led me to put the game away for a few week... which turned into a few months... and have lasted ever since. During those two decades that I've been struggling with X-Wing, not just with the difficulty, but with the basic motivation to even keep playing or to return to playing - during those two decades, there's half a dozen other games (including of course Wing Commander) that I've returned to and replayed repeatedly, with great relish and enjoyment. So, it's not that I lacked time to play X-Wing. Rather, X-Wing's frustrating gameplay model has that effect where, whenever I think about playing the game, I shrug and say to myself "maybe next year."