Isn't it despise, shielding oneself from everything, and gain the wish to reset the world? Exactly what Shinji desires in his heart, i suppose.
He thinks, that everybody should die. Nobody needs him and therefore everybody stays "untouched" even if he wasn't there anymore, so he hates the world.
Also partially aspects from Aska included:
She thinks, if everything of him can't be hers, she doesn't want him (Shinji).
She was the last person, Shinji thought who could help him. It is very selfish of her, like a child...the song could be a childrens clapping song too, without the text.
"It all returns to nothing" is obviously repeated continously and the "world is tumbling down".
Originally it was planed to use the song "Everything you've ever dreamed" for the scene in the movie.
ARIANNE is a singer, NOT japanese, sometimes performing with LOREN&MASH.
edit:
Anno is strange and very talented, i like his "early" work and the part in Nausica where the God Warrior melts down.
http://upload.wikimedia.org/wikipedia/en/c/ca/Nausicaa_god_warrior.png
All done by himself, very impressive scene.
I recommend to watch his live-action 8mm-like digital movie, it's called "Love&Pop" (there are two, but the original from 1998, directed by Anno is good)
http://www.imdb.com/title/tt0168972/
on imdb, this is a false cover...
http://www.amazon.co.jp/gp/switch-language/product/B00005F5TM/ref=dp_change_lang?ie=UTF8&language=en%5FJP
don't watch the 2004 version;)