For me LO has the obvious Balmain nostalgia, also my family was from the area so it was a real family/club atmosphere. And because we played half our games there, we'd regularly go to Grandpa's place and walk down the narrow streets to the Oval. That's a totally different beast/experience than something like arriving on a train at Homebush with 15 thousand people and fanning out onto a massive Olympic promenade.
Then when you get to the match, I like the viewing experience. I like watching footy at old grounds, I like that it harkens back to older decades. LO reminds me of things like "around the grounds" on the radio, Laurie Nichols, buying peanuts on the hill whilst sitting on a picnic rug etc. That's pure nostalgia in a bottle there, no shame.
And LO isn't quite as quirky as some of the other old grounds - e.g. Brookvale is not a great design for viewing the match, though I can appreciate it's old-school Manly. Belmore has that eyesore train line and mounting yard sheds at one end. North Sydney is picturesque but rolls downhill and has a huge tree down one end, with the grandstand viewing the field at an oblique angle.
LO gets used so much because it was redesigned in the 1970s specifically to provide night-time lighting (which is why it hosted so many Panasonic Cup games) and run N-S (to avoid sun in players' eyes), for up to 20 thousand people. That was just right for NSWRL and all the other rectangle-field events it did and still hosts (e.g. junior footy and soccer).
