Long Beach Airport (LGB) in California is a facility that still requires passengers to walk outside to the planes. The airport authority spent $136 million upgrading the main terminal, but decided to keep this antiquated method instead of installing indoor connections between the terminal and planes.
The lack of jet bridges is the main reason I avoid LGB. The worst flight I ever had was a red-eye from LGB to Fort Lauderdale. It was between Christmas and New Year's and a winter storm was hitting Southern California. Airline/airport staff were trying to keep passengers as dry as possible by loaning big umbrellas to walk from the terminal to the plane. Unfortunately, I got stuck outside just a few feet shy of the door. It was only 2-3 minutes, but I was soaked from my knees to my feet due to the wind and lack of a full-body trench coat. The umbrella simply wasn't enough protection.
Once inside, the Flight Attendent was mortified. She said they'd tried to get people into their seats to get us out of the rain, but people didn't comply. It was a miserable 5 hour flight.