5. The "Nolanverse" is Too Good
It just wouldn't be fair on whoever comes next to go for an all-out reboot. Leave the gritty realism behind and people will cry "Schumacher", but restart the franchise in the same vein and the same people will deride it as a copycat. Darren Aronofsky was famously dropped from Begins in favour of Nolan and, should he have unfinished business, it would be interesting to see his take. But short of that highly unlikely instance, it's difficult to see how a reboot would be anything other than a target for criticism - fair or otherwise. Some will say the series should end on a high and avoid falling into self-parody like the previous films, but if placed in good hands and overseen in some way by Nolan (even as a producer) there is no reason why we should ever return to a world of neon lights and Bat-nipples.