While the LAN experience is certainly different from playing online, I feel that it was a necessity at the time. You had to choose between slow, laggy and unreliable online or snappy awesome LAN, the choice was clear. Nowadays I feel that it's more of a nostalgia thing, like people who like to read dead tree newspapers instead of online news etc.
I'm not saying LAN isn't viable, but broadband has made it obsolete, it's pretty much a niche thing these days. It's hard enough to get people together online, getting them together in real life is pain.