Why the sudden popularity of 12 inch arms

Well, I think, there are some reasons why the 12's are back.
Mainly based on marketing reasons, because they can be sold.
That's it.
The technical reasons, well, most manufacturers are not stupid, they know how to build a good arm, some offer both, sell both and honestly, who cares. Some of them say, no one needs a 12 Arm, some reviewers write, they can not live without one....
In a way, it is like Raul wrote, when you have the perfect match, no one cares. Some time ago I listened to such a match and honestly, I simply couldn't believe it. It was a old FR64 Arm with a Koetsu on a real super Turntable.
When I closed my eyes ( a "Blind test" ) I really thought " I'm listening to an Air Tracking Arm". But, the Table was really a good one.
Some Arms can compensate Errors from the Turntable/Cartridge more or less, but at the end of day I think, the 12s look cool.

Zieman, I have no problem with your answer to the OP. The point I was attempting to make was the caution that a 12" arm will not automatically be an improvement compared to a shorter arm. Some might infer that from your post, particularly with your emphasis that only the arm was changed.

There are many design/construction differences between your 312 and your Lustre and I believe that was one of your points. That supports the position Raul has stated many times - many elements come into play in matching a cartridge with different arms. For whatever combination of reasons, your cartridge sounds better in your 312. One should not assume it was just because your SME is 12".

I believe you understand this so I was trying to offer a clarification to readers with perhaps less experience. Peace.

Thomas, Thanks for breaking the ice on the looks issue. Perhaps how absolutely beautiful this thing looks has an effect as well! Visually stunning piece of work. I'm going to go back and just look at it now! Z.

No sweat Pryso. The original question, which seems to be so quickly forgotten in some of these forums was why the sudden popularity. Technology and mat'ls are why the disadvantages can more easily be eliminated. I can hear the geometry change with most "short" arms. The technology now exists and is affordable to hang the cart way out there like never before. SME thinks enough of the improvement to build a 20/ series table just for this length arm(s) When was the last time SME latched on to a fad or a marketing scheme? Z.

Dear Zieman: +++++ " Raul, Please read my response again. Slowly. I changed one component. The only proper way to evaluate a new addition. " +++++

IMHO I think that you missed what a tonearm involve in sound reproduction performance, you can read my post again or better yet read what Pryso posted about whom understand perfectly the subject:

+++++ " You may have changed only one component but you changed multiple parameters. Not only degrees of tracing error but also mass, stiffness, bearing design and quality, resonant frequency, and wire (considerations just off the top of my head) " +++++, build material, tonearm shape, counterweight position, etc, etc. and Z it does not matters with which cartridge.

Regards and enjoy the music.
Raul.