The same reason that beer tastes bad from a can--you don't get the smell.
I beg to differ. Beer tastes better from a glass bottle than from a can. The smell doesn't account for everything there.
Perhaps the can smells bad, and the glass bottle smells neutral.
I've heard it's supposed to taste better in a can, because a can is better-sealed than a bottle and offers better protection against sunlight. Though personally I can't tell the difference.
Because not all volatiles taste good, or appreciate aeration?
The same principle of 'temperature matters'. Some things are better cold.