I have mixed views re. airbridges; they're great when it's raining but clearly have their limitations:
1. Turn-around time as mentioned. The operator always seems to take ages aligning the bridge to the front door which just adds more time.
2. Boarding from stairs is more fun; you appreciate the sheer size of a large a/c when this happens.
3. Most airports only have single airbridges ie. no boarding at the rear door which is a real pain on large a/c. The gates on Pier F at AMS are impressive; the overwing airbridges must have cost a fortune.