I think most people that "like star wars" during the time those were written never engaged with the expanded universe in a way that this affected them.
I declare SMALL
As someone who WAS very heavily engaged in the EU through the 90s and early 2000s, I find that statement rather dissmissive.
Star Wars EU was always noncanon according to George Lucas even when the stuff was being written. Still amaze me that Star Wars fan act like the Mouse actually changed that when they didn't.
Okay, leaving aside the canonicity of the EU, then: even so, the sheer amount of material that was basically scrubbed eclipses BT's retcon several orders of magnitude.
I mean, frack, it covers (as bobthecoward said "gaming" and not "wargaming" or "tabletop gaming"):
X-Wing/TIE Fighter/X-Wing verses TIE Fighter/X-Wing Alliance
Knight of the Old Republic 1, 2 (and the MMO, I think?)
Star Wars Supremacy
Star Wars Empire At War
Star Wars RPG D6 (two editions)
Star Wars D20 (three editions)
As, as we're talking lore changes that impinge on those:
The Star Wars Essential Guides
The Star Wars Technical Manuals
And I'm not even going to guess how many novels.
(And that's just more or less stuff I can think of from my
own collections of stuff, off the top of my head without trying terribly hard.)
Retconning out... About as much real-world time history as BattleTech has actually
existed... (and probably in the running for as much written words as BattleTech has evr produced alone...) Is a
pretty major retcon.
And I also add:
quality of retcon was not in the question (and I have excised any of my own commentary on that), only size and significance.
(I mean, personally, I wouldn't even have known there WAS one to BattleTech, because I only started BT at (ironically) about the same time as I got really into Star Wars - in the mid 90s. It's kind of hard to miss the entire EU being retconned, though.)