STTNG was the last pinball game to sell over 10,000 units. Probably a combo of great theme, Steve Ritichie's track record, and the recent memory of TAF for operators.
I don't remember seeing it on location back in the day, and never played one until I traded a Black Knight for one 10 years or so ago. My guess is - like TZ - it was a tough game to keep running on location.