I know what you mean about the pictures. It depends on how and what they were.
You should always have that one for the thumbnail though. Can you believe some people don't click links without thumbnails. I remember the days when a thumbnail was precisely that.
To be fair, many of the posts without thumbnails are low-quality spam.
The problem is really that there are many posts whose main focus is the text (such as my own) which aren't too low-quality (Not mine, then), and people who avoid posts without thumbnails miss them.
I mean really, would you avoid people just because they happened to lack thumbnails? I probably would, they'd look fairly horrifying, but with your whole evil clown fetish I can never know for sure.
I give scant regard for thumbnails!