When the original LoZ was released, it made "non-gamers" into Zelda fans. It DID appeal to the expanded audience like how World of Warcraft makes kids growing up into gamers as well.
The game was damn good, vast, and people wanted to play it. THAT'S the expanded audience. "When its good enough to make people obviously see the quality within it." Not "The game is easy and not that complicated."
In terms of 3D Zelda's, OoT and MM are definitely the best in terms of important exploration. OoT let you do dungeons out of order (even WITHOUT glitches) just like ALttP, and OoT had awesome items that made the game easier, such as biggoron sword, magic spells, fire/ice arrows, powered=up spin attack, increased magic meter bar (which all games except for TP had) and heart pieces felt at least needed "enough" to want to explore for them to increase your health somewhat. Skulltula's were also hidden nicely and the rewards for them were very cool. The world just plain felt more vast and rewarding, life-like. Majora's Mask also had a good amount of this and in some ways (emphasis on "some ways" here), even more than OoT.
However, even OoT and MM seemed to drift compared to previous Zelda games. With Wind Waker and Twilight Princess, it has drifted far more since then. They can't even compare to the first two 3D Zelda games (in the senses I'm talking about. If you like WW and TP more than other Zelda games, then more power to you.), so just think how far they've drifted compared to LoZ and ALttP.