I think that there is a difference between the first set of issues (developer access, backup failure etc) and not maintaining a current patch level.

Its like most things, down to judgement - you don't want to be rolling out every SQL KB that comes along, while on the other hand not planning to apply the next SP until support runs out for the current one is not a good idear either - although mea culpa I have held back on upgrading from SQL2008 R2 Sp1 because there really hasn't been a need to and the SP on our estate has been very stable 😉