I actually just had my first one in the last game I played. I was so excited when I went to the analyzer and when I saw the move it graded brilliant, I was underwhelmed. It was a great find but I've had much better moves, even in that game.
Chess.com updated their analysis/review mode last month or so. I like the review mode with the coaching, that's really cool. They also added "great move" between excellent and brilliant, so I suspect they must have made it a bit easier to get a brilliant move? That would explain why we're seeing more now.