I think it's memorable because they killed the "nice" girl. Usually that doesn't happen. It's kind of like the movie Psycho where they kill the main character (or one of them) halfway through the movie.
And even though she was dead, she is the one that actually saved the world at the end by destroying meteor. Some say "But Cloud killed Sephiroth!" Yes that's true, but Cloud was always stronger than Sephiroth as proven in the flash back. He just couldn't get to Sephiroth because of the barrier he put around the Northern Crater. It wasn't until Shinra got rid of the barrier than Cloud was able to go after him.
The main problem was meteor which was going to crash into the Earth and destory it. Without Aeris, meteor wouldn't have been destoryed.
And even though she was dead, she is the one that actually saved the world at the end by destroying meteor. Some say "But Cloud killed Sephiroth!" Yes that's true, but Cloud was always stronger than Sephiroth as proven in the flash back. He just couldn't get to Sephiroth because of the barrier he put around the Northern Crater. It wasn't until Shinra got rid of the barrier than Cloud was able to go after him.
The main problem was meteor which was going to crash into the Earth and destory it. Without Aeris, meteor wouldn't have been destoryed.