japan sales have been doing great during the first month of 2008.

if you'll notice, sales started going downhill at around february, which if i'm not mistaken, is about the same time that the 60 gig model was discontinued in japan. 

imo, sony should have kept 2 skus in japan, or if they had to just maintain 1, they should have kept the 60 gig model.

either that or i'm just delusional.

The PS3 was finished even when it did have BC. There's nothing that can be done to help the PS3 in Japan. The console has already died.

It still doesn't make sense that they removed backward compatibility.

 it was to save on manufacturing costs

I agree that was the reason but the cost alone wasn't the problem. The issue is the consumer has to look at a package and say "The price I'm paying is justifed by the value of what I get in return." and the money they were able to save by removing BC lowered the perceived value far more than what they saved for a lot of people. 

The value of BC to a consumer is greater than Sony seems to have anticipated.  In an ideal world this would mean they just add it back in and sales will be fine again...but this isn't always the case in reality.  I hope they do re-add BC to the console as it is really one of my pre-requisites for buying the console.

But isn't that the same half-assed software BC everyone criticized the Xbox 360 for, with which only some games will work 100% correctly?

During this generation, the Wii is the only console which got backwards compatibility right. For me, it's an important feature. I'm playing REmake (GC), Ninja Gaiden Black (XB) and SSBM (GC).

The sooner Sony get the 80GB with BC out in all regions to make them all have the 40 and 80GB models the better!

statistics 1.1: correlation is no proof of causation.