I agree with most of what you've said (I used to work for a company that did transport data applications and worked quite closely with TfL so I know the arguments in favour quite well). However, the design of bendy bus used in London was really intended for continental (particularly German) cities with large ring roads with a dedicated uninterrupted bike (EDIT: "bus", not bike sorry) lane. Anyone who has ever watched one trying and failing to make the turn out of Gower St, for instance, and blocking the traffic for several phases of the lights knows that TfL have been over-ambitious in the routes they've given the bendy buses. Problem is that with the Tube PPP having been such a failure, buses are the only area of public transport that has been able to expand its passenger capacity significantly in the past decade, so we're probably stuck with an ever-increasing number of them.
@Oliver:
I agree with most of what you've said (I used to work for a company that did transport data applications and worked quite closely with TfL so I know the arguments in favour quite well). However, the design of bendy bus used in London was really intended for continental (particularly German) cities with large ring roads with a dedicated uninterrupted bike (EDIT: "bus", not bike sorry) lane. Anyone who has ever watched one trying and failing to make the turn out of Gower St, for instance, and blocking the traffic for several phases of the lights knows that TfL have been over-ambitious in the routes they've given the bendy buses. Problem is that with the Tube PPP having been such a failure, buses are the only area of public transport that has been able to expand its passenger capacity significantly in the past decade, so we're probably stuck with an ever-increasing number of them.