Well, I bought a few L series lenses a few years ago, and most of them have increased in value. It's the bodies that diminish in price. Naturally so, since the sensors keep getting better. That's one of the regrets I have regarding digital photography. Back when I bought my first Nikon F, I felt it would always be there for me. It was. Right up to the point when I bought the Canon 20D. I would never buy a Leica M9, since it will be worth quite a bit less in five years in my opinion.
It's the nature of the technology. I wish I only had to buy new film to get the benefit of the latest technology. And my Nikon F made ME focus the lens.
The point is NOT that gear depreciates. This is a given and you have to accept that.
The point is that Canon is playing
pricing games, like neither they nor Nikon has ever done before, and they are pricing their products 20% higher for the first 6 months than is "normal". This means your depreciation goes from 1% per month to 5% per month.
Nothing depreciates that fast. Not even a car when it's driven off the lot. It's mind blowing.
It's so crazy that it would almost as expensive to RENT the camera as to buy it.

In fact if cars companies took pricing from Canon's recent products, you'd be paying $1,000 a month to lease the redesigned 2013 Honda Civic.
So it's not the depreciation, it's the incredible level of depreciation.