The issue aren't the people, it are the circumstances the presented reasoning is based on.
You for instance seem to imply that the pricing of a one off production run limited to less than 100 units remotely reflects on the costs associated with a 135mm 1.4.
And we saw many comparisons with the current big whites, but those are EF lenses designed for a different system and manufacturing process. They are also aimed at a different kind of photography that may not be purchased in such great volumes as portrait work. We don't really have enough RF mount lenses to draw conclusions on just how much easier and efficient it is to manufacture the new lenses.
I doubt this lens will materialize if it isn't affordable enough. The great strength of the current RF mount cameras is portrait work, among other things. Giving portrait photographers an option they can't get for another system doesn't really make sense if they can't get it anyway because it is beyond their budget. That just makes the other systems more attractive because they have 'small', 'affordable' 135mm portrait options.
My principle argument has always been that the best guide to the pricing of a hypothetical 135mm f/1.4 from Canon (assuming it has autofocus) is to look at the example of the great whites eg EF 200mm f/2.0, EF 300mm f/2.8, or 400mm f/2.8. Canon would be doing well to keep the weight of a 135mm f/1.4 down at around 3kg even after the addition of the autofocus mechanism. At 3kg it would put it in the same weight class at the 200mm f2.0 (2.5kg), 300mm f/2.8 (2.3kg), 400mm f/2.8 III (2.84kg). It would also be a similar high-end category of lens, several ranks above Chinese third party manual focus lenses like the Mitakon.
The reference to the Mitakon price is simply that it corroborates this notion that high-end glass in this circa 3kg weight category cannot be expected to be cheap, especially since it is being made by Canon...and NOT by a third-party Chinese manufacturer. Nor does comparing with this hypothetical circa 3kg high-end lens to the price of a consumer zoom lens of a similar weight or front element size by Tamron or Sigma provide a helpful comparative price point.
As for the notion that a 135mm f/1.4 will sell like hotcakes, I am rather sceptical. I own the Canon 200mm f/2.0 and it tends to be a studio lens. It's rather too heavy to be able to carry around with you all that much. I couldn't imagine a wedding photographer carrying it around all day instead of, or in addition to, a 70-200mm f/2.8. I was seduced by the thought of the f/2.0 aperture but it's a lot less practical than I thought.
Just because Canon are making this 135mm f/1.4 for the RF mount, it isn't going to make the glass super cheap. In fact, the opposite is true. The Canon RF 24-70mm f/2.8 costs $2300 USD (B&H current price) vs $1600 (on sale at B&H from the usual $1900 USD) for the EF 24-70mm f/2.8. If anything, the new RF lenses are looking like they are going to be more expensive rather than cheaper, especially if they are being designed with a 100+MP sensor future in mind.
Some might point out quite rightly that Canon are patenting optical formulae that help reduce the size of the lens. That's how they got the size of the 600mm f/4 to 3kg on the Mark III, down from 3.9kg for the Mark II version. However, the weight reduction is accompanied by a price hike from $1,370,000 yen to $1,820,000 yen (Canon JP website, the US price for the Mark II looks discounted)! The use of a lot of aspherical elements in the patent for the 135mm f/1.4 suggests that they are using them in a similar way to reduce the size of the lens. That means it might be possible to keep the weight at around 3kg or slightly less even after the addition of autofocus. All that does is put it in the same weight category as the 200mm f2.0 (2.5kg, $5699), 300mm f/2.8 (2.3kg, $6099), 400mm f/2.8 III (2.84kg, $8000). It simply becomes inconceivable that Canon would sell a high-end lens in this heavyweight-class for thousands of dollars less than these comparative great whites. If you're a diehard optimist then hoping for around $5500 might be the closest thing to a nice bargain for a 135mm f/1.4 with autofocus that you could realistically hope for. Anything less and you might as well hold your breath in expectation of the tooth fairy visiting soon.
Being told that the tooth fairy doesn't exist needn't be received as apocalyptic doom and gloom news. It's just about being realistic rather than falling prey to wishful thinking. It's better to face up to reality sooner than living in fantasy land for longer. Sometimes you also have to be careful what you wish for. You are going to find this circa 3kg beast a lot less practical than you thought it was, and it might end up a white elephant.
