I probably wouldn't care about Earthbound if it weren't for Smash Bros.
That's how I got into EarthBound too. I was wondering where this "Ness" fellow came from. Somehow in the back of my mind I always knew about EarthBound, but I needed to play Super Mario RPG before I actually liked RPGs. After that, I was looking back for RPGs I'd like... and since I didn't like the whole fantasy theme, EarthBound's modern setting seemed right. Maybe it was the newspaper-style preview and the "This game stinks" stickers that made me remember it. Along with a screenshot of Ness digging through a trash can to find a hamburger.
And since it took me ages to beat EarthBound (okay, 3 weeks), I wasn't thinking about any other SNES RPGs I might be interested in playing, until a friend introduced me to them.
Although I like EarthBound and Mother 3, I don't consider them to be the best RPGs ever made, and I usually go to other RPGs when given the choice. But they're a safe bet when you want an old-style RPG... be prepared to level grind like crazy though.