Why the sudden popularity of 12 inch arms

Inpepinnovations...When my cars had drum brakes the shoes had to be replaced at about 60,000 miles. At that time the drums would be turned (remachined). Nowadays, with disc brakes they go in as few as 25,000 miles, and the rotors are so thin that they can't be remachined, so you need to buy new ones. But the disc brakes do work well.

Disc brakes were first used in aircraft, and next in race cars, where light weight compared with drums, was the main advantage.

Okay, This ought to be good! Please tell me what I am missing here. I can't find a drum anywhere. My '67 XKE had discs. (poorly executed) That was, by my math, at least 40 years ago. That's "19"67... Let's check in shall we; this IS 2008, right? A Nissan Sentra has discs. A Hyundai has discs. My BICYCLE has discs... Back to fifth grade science again; metal expands as temp increases, with me so far? Drums GROW when used, (the whole idea behind brakes!) The shoes get FARTHER from the drum the more they are used. Becoming ineffective. (opposite of the whole idea behind brakes) Ever wonder why those runouts are built on the DOWNHILL side of the road? Got any idea how they slow a FREIGHT TRAIN down? An Airplane? You are just messing with me, right? Discs are bound by the same physics (sorry, it's true) they also GROW when hot, getting CLOSER to the pads. Becoming MORE effective. You are laughing, aren't you? Same goes for carburetors too, right? Blows fuel injection away, when it's done right? How about you rattle off a few examples where that applies! If you are still using a quill pen and an Abucus, how did you access this thread? OH NO, not utilizing modern technology! NNNOOOO!!!!! Z.

Mr E, Back when your cars had drums (I think they were actually called Horseless Carriages, right?) the vehicle didn't last 60,000 miles, come on! Your perception of increased stopping power is correct. As power increased, and traction improved (or are you in the bias ply camp too?) wear, temporarily increased. Ancient history. Lighter weight, not so sure... Certainly not today. (Think ceramic) You posted from a computer, yes? The "good old days" really weren't, were they... Z.

BTW,"Z",I happen to like the person you seem to be critical of.I like his enthusiasm,and his well meant intentions!!Always have!!
Like everyone shoud do with my comments(I must come off as hot air,often)some things should be taken with a grain of salt.So,I like when we get ALOT of varying opinions.I've gotten myself into alot of trouble with my own poor interjection of some of own opinions.I "think" I've learned from "posting" experience,over time.The opinions I disagree with I throw out,and the other ones I attempt to learn from.
Don't take this as a wrist slap,'cause you are a very interesting poster.
Best.

"light weight compared with drums, was the main advantage." What about resistance to fade and ability to work in the wet?

Now we have REALLY gotten off topic, so back to the OP. My guess is that some manufacturers (starting with VPI I believe) saw an increasing availability of tangental arms as new product development responded to the resurgent interest in vinyl. Since the biggest advantage with tangental arms is reduced tracing distortion, decisions were made to develop arms longer than the standard 9" that might reduce such distortions without involving other issues for tangental arms. The fact that new design, material development, and manufacturing processes could overcome some of the high mass and rigidity issues from longer arms manufactured 30 years ago has been a bonus.

A second factor could be the overall upgrading in resolution of tables and cartridges so that performance of tonearms has been demanded and appreciated, whether by 12" or tangental arms.

And peace Raul. I understand that in your experience, you have not found such product development to outweigh basic system matching/compatibility. But that is another story and does not address the OP question.