--> many, very dinstinctive areas; I could easily point out where the library or chapel is while I had no clue where to go when looking at the SM map
--> AWESOME, very veried, CD quality soundtrack that didn't loop after 40 seconds or so
--> better gameplay than SM
--> voice acting
--> a story
I love both SM and SOTN and i respect your opinion but:
I could also easily point where each area in Super Metroid is. In fact its even easier because the map is splitted in areas like Norfair, Crateria, etc and you can choose to browse each map individually.
Both soundtracks are awesome. Super Metroid's Soundtrack is perfect for its setting. I agree about the not so good sound quality though.
Better gameplay than SM? In SM the level design and balance is better. The maximum "level" Samus can reach is when you get all the items. You can't get stronger than that and the game is designed around a possible fully upgraded Samus. In SOTN you can grind endlessly until you become way too powerful. Both games are great but SOTN can be a grind fest. And some items are just overpowered too.
Voice acting? Why would SM need voice acting when you are supposed to be alone on a hostile planet? Who is there to speak to? The game is about isolation, not about conversations. OtherM proved that voice acting can also totally ruin the fragile Metroid atmosphere. And really, the voice acting in SOTN is cheesy and silly at best.
A Story? Both games have a story. Just because a game doesn't have conversations and NPCs to talk to, or cut scenes, it doesn't mean it can't have a story. And Super Metroid in particular has a great story too. The last part was amazing and kind of emotional too, without having to resort in chatter and talky parts. Sometimes, less is more. Its called subtlety.