I don't have any problem with a team scoring as much as possible while already leading, regardless of sport. Pertaining to basketball, I have two points:
- You never know when a lead is safe
- What else are you supposed to do, miss shots on purpose?
It's a competition. The goal is to do as well as you can.
I'm not sure about basketball, but for other Olympic sports at least, the first tiebreaker to determine group standings is point differential, so "running up the score" can actually help you.