Curve ball here-- from someone who always dodged political science.
Aiwendil makes a very interesting point in his essay on Elvish music. To crudely paraphrase the whole essay: Elvish music does not "evolve", it "devolves". (Galadriel makes a general reference, saying that when the Rings are destroyed, the elves who remain in Middle-Earth will fade to a rustic folk of wood and dell.) They start strong, and then dwindle and fade. Furthermore it was their job to prepare the earth for men-- and men eventually take over.
Aiwendil
made this point quite well regarding elvish music-- see
Aiwendil's magnificent essay.... (edit: argh, the link requires a login-- I don't remember needing to do that before?)
I wonder-- combining the Osanwe point with the "devolving" idea. In the early years, when the elves were fewer in number, osanwe would have provided a formidable method of understanding and guiding a group of people. A harmoniously-minded elf with peaceable intentions could have used osanwe to keep the realm peaceful and prosperous indeed. Even if you did have a king-- and it seems that they started with First, Second and Third, three 'kings', so to speak-- if they majored in osanwe, what need would there be for feudal attitudes, or dictatorial attitudes, or what have you?
If the society then got used to the idea of single leaders of the kingly type (of which I'm not yet convinced, wondering about a more clannish leadership instead-- and even kings keep counsellors and councils-- but to continue) then as osanwe was used less (devolving), more crude methods of government would have been required.