I just spent time going through my preferences pane trying to get excerpts turned back on, only to find out that the option was right in front of me on the questions list screen. This made me consider two points:
Why are excerpts turned off by default? Yes, I know, it's "just a default", but it's an important default.
Should the "enable excerpts" preference really live under Edit Profile & Settings > Preferences. Or, perhaps both places? I hate settings that can be toggled in more than one place.
If I'm wrong, and the excerpts are already enabled by default, leave a comment and I'll edit this question.