Why is the price of new tonearms so high

Ok, lets not go there then. Ill approach from another angle.
Lets say we have a good cart like the XV-1s, I believe will match with a medium mass arm from its 8x10Dyne, if we have a heavy arm, say 30g like the 66s, wouldnt the performance be worse than in a less "rigid" but lighter arm?

The XV-1s is 10x10 Dyne not 8.

As for my "beloved" FR-66s - its effective moving mass can be reduced considerably by using a lighter (- Orsonic etc.) headshell. The DV XV-1s does perform outstanding good in both - the FR-64s and FR-66s. This is due to the extreme rigid design of these tonearms in conjunction with their tight bearings. This allows for exceptionell power transmission from the cartridge through the tonearm and away into the base.
These mechanical facts do give a very detailed, transparent yet ultra-dynamic sound with a very convincing "physical presence" of the sound.
Thats why almost all - save for the very lightweigt and high-compliance - cartridges do perform surprisingly well in the heavy FR-tonearms.
So - yes, the FR-tonearms are NOT ideal matches in terms of compliance, but their mechanical advantages do outweight this one non-compliant detail.
In general, the "heavy" tonearms do have plain advantages (some a bit - some a lot) in power (read: vibration emitted from the cartridge during playback) handling. This is due to their usual heavy duty (compared with lighter tonearms) bearings and to the use of steel and similar materials for the armtubes which do allow fast transient transmission.
In the very end, a tonearm performance comes always down to and is always rooted in its mechanical and geometrical cornerstones.
In any comparism, always take care that the cartridge is aligned to the very same geometry in all the tonearms under survey.
Cheers,
D.

Hi D.,
>>> In general, the "heavy" tonearms do have plain advantages ..in power (read: vibration emitted from the cartridge during playback) handling..<<<

A question: What about, the higher the mass, the bigger the "acoustic capacitance" leading to a 'smearing' in time of information?

Energy is "stored" longer and released later with higher mass involved. An accepted principal with dynamic drivers, etc. (also note what REGA's Roy Gandy has to say about that regarding HIS arms and decks...)

What say you?
A.

Ax,

I don't think that applies to tonearms since a tonearm does not produce any signal. The tonearms job is to provide a robust platform for the cart and stylus, which together produce signal. Stiffer styli require a more massive tonearm/platform (more inertia to overcome) in order to produce the best signal. That is typically measured as cart/stylus compliance I believe.