As noted elsewhere that comments take up a lot of vertical space and attention on a page. While it isn't costing any more votes on a deleted post, it still is distracting.
With comments on deleted answers of undeleted questions, automatically and always fully collapse them requiring a click to see them.
The vertical space and bandwidth they take up is unnecessary unless you want to read them, and then the full context is often better than the 'top voted comment' context.
