I think so too. I don't know whether submissions shouldn't give any karma, but in my opionion it should be limited. For instance they could start out with 0 points and the submitter gets a point for every 50 upvotes the story gets or something like that.
Another possibility would be to seperate submission and comment karma and may be have them limited in some way as well. There is currently a big mismatch, you'd need ~5 highly "appreciated" comments to get the same amount of karma one medium apple story "earns" you. This makes karma as - some sort of metric - less useful.
Regarding the "laughs" I don't really understand what the big deal is. I like a funny/sarcastic (read: not stupid) comment that shows at least some insight or understanding of the matter or just pokes fun at a particular view. This is necessary and healthy for a discussion.