"Random" evolution does seem to do a much better job than our clumsy attempts at domestication and eugenics. Still, even though domesticated animals and plants may not be overall viable creatures, they usually can be forced to do one thing much better (produce grain or win the Derby) than their wild cousins.

True. The word "better" depends on context. But if you are setting an organism (or a culture) out into the world to be independent, a robust variety of available genes (or a flexible and variety-filled culture) is going to do better in that arena. "Wild" evolution makes mistakes all the time, but if there's flexibility built in, they can often correct themselves. Higher organisms or cultures that are "stuck on stupid" often fail. I'm not comfortable taking this analogy too far--I can already see a few small holes in it.

But I digress...in spite of this, there may come a time when we may be forced (perhaps because of space exploration) to engineer a culture; for example, to prevent friction between multicultural crews of generation starships or O'Neill colonies. Recall the Free Traders in Heinlein's Citizen of the Galaxy?

Possibly. Cultures that have had to deal with hostile environments and limited resources have sometimes tended to be a lot more regimented, particularly in larger populations.