While Hussar furnishes a much more concrete answer...I don't know...I'm not sure why it is and it was before my time but I've seen that B/X speaks to people in a profound way (I think it was Ron Edwards who told me it was 'the best' edition of D&D in his opinion, but I can't be sure on the 'famous' person nor the edition). I would guess that it has something to do with a certain age that a lot of people belonging to a certain generation of gamers were at when it was released.
Tangentially related at best, but the same phenomenon: I think I was around 11 years old in the summer of 1997 when HBO started airing its phenomenal Spawn animated series (which I strongly recommend: it is literally as good as the contemporaneous Spawn live action film is bad, and that's not hyperbole, I KNOW how bad that movie was). So I was on the eve of adolescence and pubescence and all that stuff and here comes this (actually quite terrifying) series that airs at midnight on HBO after my parents have gone to bed and it's absolutely filled with supernatural horror, graphic violence, a cornucopia of swearing, and cartoon boobies, surrounding the edgiest superhero comics character I'd ever seen (he had Ghost Rider's chains, he had Venom's living costume, he had Keith David's voice (!!!!), he was LITERALLY FROM HELL, his enemies were angels, demons, shadowy government conspiracies and serial child murderers, not costumed nitwits and he swore, delivered incredibly badass catchphrases from the darkness before appearing behind some a-hole to twist his head off, suffered emotionally like a real person, killed bad guys with guns, and just generally did things I'd never seen comic book characters do before). It was transformative. I got into the comics pretty much immediately thereafter, and while they were certainly better than the live action movie, they didn't measure up to the HBO series--probably because HBO was just growing into the more-than-a-decade of dominance it would have over the "seriously good television" market and it had an AMAZING crack writing team in place to preempty and correct Todd's worst and dumbest impulses. Indeed, to this day, the Spawn cartoon is the epitome of cool. I don't think that's entirely because I haven't matured at all since I was 11, nor do I think it's entirely because the show was actually extremely well acted, animated (there is a quantum leap of improvement in the animation quality between the three seasons that were produced), and written, I think it's kind of both. But when I first saw it on HBO some time after midnight in the summer of 1997, something was planted within me that this was just the coolest freaking thing ever, and that little pearl of childlike amazement or whatever is still there.
Final Fantasy VII had a huge impact on me for largely the same reason: the age I was when it came out. Although in that case, the first hook that Final Fantasy VII got in me was how incredibly similar (it seemed to me) it was to Shadowrun.
Anyway I think B/X may have become beloved of an entire generation of gamers by a similar process.
