We returned to LA on Friday after a few stops, the last being Ensenada. When exiting the ship there were 2 lines in the terminal - one for US Passport holders (And Canadians with passport) and one for "others".
We were directed to the passport lineup, passing a very long line of 150-200 people being processed by maybe 4 or 5 agents. We had I think 4 agents processing us, and when we got to the entrance there were 2-3 families in each line. Total wait time: 5 minutes.
You may not require a passport to visit Mexico (Us Canadians do not require a passport to visit the US or Mexico at this time) but it sure speeds up the process. I hate lineups so that has been $65 well spent. I think in those cases it pays for itself after a few trips.