Google Search Appliance was used by thousands and thousands of big corporations - so to say it didn't get much traction is not correct. For many years it was the defacto solution for enterprise search solutions.
Huh, I basically never really heard of it being used. Guess that's the trick with 'enterprise solutions' outside of explicitly looking for it or it popping up on an aggregator like HN or /. (since this was starting in the mid '00s) you don't really hear about them.