The history of articulated buses in London is not that rich - they were introduced in 2002 by the previous (and probably the next) mayor and were then promised to get rid of by his successor. The idea itself is controversial - generally, bendy buses are loved by those who ride them and hated by road users.
Bendy buses are more capacious, but mostly thanks to their standing space while it is prohibited to stand at the upper deck in double-decker. So your opinion may vary depending on what do you prefer between waiting for the next bus but having a seat or being able to squeeze even into the packed one.
Thanks to the three doors and multiple Oyster card readers boarding a bendy bus is easier and quicker than a double-decker with its two doors working in one direction only. At the same time, that makes fare evasion simpler, rendering the advantage of the cheaper vehicle and service unimportant.
Also to note, those particular Mercedes buses had some weird engines problems which resulted in them catching fire several times. They were all modified to prevent that, but still the last accident happened right in our area only a couple of months ago.
Today we decided to take a "goodbye ride" by boarding the 73 to Stoke Newington, but after three or four stops the bus broke and driver asked everybody to alight. Coincidence, but that made it even more symbolic.
Goodbye, long friends - you'll be hardly missed. Especially by cyclists.