Why the sudden popularity of 12 inch arms


VPI was the only mainstream manufacturer for years, now we have 12 inch arms from
Kuzma, Schroder, SME, Consonance, Brinkman to name a few.

Why is this?? fad or long term

Would a 12ich Grahham, Triplaner or Basis be a better sounding product??
downunder
On paper a 12" arm is superior, but when it comes to manufacturing one it is not so easy. I think the combination of technical advancements, lowered manufacturing cost (or conversely the reduced aversion to a high cost arm), and the need to expand the product line (as others have said) are driving this. We are a fickle bunch so the desire to have the latest and greatest has a lot to do with it to.
SME has been making 12" arm for years, Japanese especially loves the old SME 3012 and some 3012 were made with beautiful gold plating. Genesis168 pointed out the key point and that's why 3012 is a favorite of Japanese who value musicality over speed and detail.

SME moved away from 12" arm for years when they introduced SME V/IV/309 family, but now they are introducing 12" arm again. Market demand might be the reason for the re-introduction of 12" arm.