The problem is that we never hear of the events in the games in the books. DE got more credibility in my eyes because it is in the books.
The fourth mission of X-Wing was referenced in Rogue Squadron. (The mission where the player has to protect the medical frigate and the corvette Korlev against the Imperial frigate Warspite.)
According to LucasFilm's policy at http://www.starwars.com/community/askjc/steve/askjc20010817.html
, "game material" has "room for interpretation." Especially when we keep in mind that "a video game has to take an interactive approach that favors gameplay."
So the part that makes gameplay fun is what can be discarded. I mean, I don't think anyone thinks that Kyle Katarn can take multiple blaster hits to the head, or that he infiltrated multiple Imperial bases in Dark Forces and completely sanitized them all (well, that's what I did)... or that he can carry all those weapons in a tiny backpack.
But the overall idea and storyline is valid. Kyle did retrieve the plans and send them off to be transmitted elsewhere (X-Wing shows further steps the plans went through to reach the Rebellion), but I find it far more likely that he kept a low profile while in the Imperial base. And he stopped the Dark Trooper project, but was most likely a lot less reckless than I was...