Every song conveys its own story. If you do not express a story in the song, at least to me, it's either a good mood song or just useless to listen to. Music is supposed to make you feel something. Not every song is a piece of real music in my opinion.
Yes, emotional songs. A song that makes you laugh because you know that feeling and feel like you're really there or a deep sorrow that makes you empathetic or sympathetic for the characters! XD
Love to Love gon to heartbreak is... kinda... don't get me wrong I love my romance but that's pretty much ALL that comes on the radio. How often do you hear a song that tells you about a mother who kidnaps two babies and kills the mother? LOL
Yes, that is why they sing in one genre or mood and that's all fine and dandy- but that doesn't change the fact that it limits them and their voices. XD
A real human's voice is nice, yes, but vocaloids are just.. better. Unlimited amount of range music-wise, different types of humor and angst and love that anybody anywhere can relate to- it's just more interesting and more intriguing of an idea. Normal voices are... boring. They aren't outdated but... they're boring. And when you auto-tune it it just sounds... you know what it sounds like. I love listening to either but anime mixed with original mysterious music is what'll catch me.
A story is what matters to me. A story is what makes me feel and what makes me smile or laugh or cry or go "wtf? O_o". Random sounds/rhythms/lyrics just isn't as fantastic as a song with a purpose to me.