Full Idea
The suspicion is that the necessity doesn't arise from how worlds are, but rather that the worlds are taken to be as they are in order to capture the intuitive necessity.
Gist of Idea
Worlds don't explain necessity; we use necessity to decide on possible worlds
Source
Michael Jubien (Analyzing Modality [2007], 1)
Book Reference
'Oxford Studies in Metaphysics vol.3', ed/tr. Zimmerman,Dean W. [OUP 2007], p.105
A Reaction
It has always seemed to me rather glaring that you need a prior notion of 'possible' before you can start to talk about 'possible worlds', but I have always been too timid to disagree with the combination of Saul Kripke and David Lewis. Thank you, Jubien!