Japan is still 2nd largest gaming market worldwide and Japanese games is different compared to Western games. i think Sony delay PS4 in Japan they want to crush Xbox One in US and Europe. US getting earlier than Europe because that is Microsoft biggest market then followed by Europe where Sony is bigger but Xbox still competitive. Japan is Sony/Nintendo territory and Microsoft wont have any chance there.

Isn't that M$'s plan already?

Aren't they supossed to launch on 13 countries and the next year on the rest? 

It's a good sized market, significant enough in the big picture. It's more important, however, because of its high concentration of developers. Winning that audience and wooing its developers can be very influential worldwide. Think about this (unlikely) scenario: Sony and MS ignore Japan for a year, Nintendo launches a slew of big games and new IPs and takes over the market, selling 15-20 million Wii U's. Sony's lack of Japanese focus results in a small market share less, than 5 million. Konami makes Metal Gear Solid 6, Square makes Final Fantasy XVI and Namco makes Tales of Spurgeonryan. Are they going to release these popular-in-Japan titles only on a system with a small Japanese footprint? The answer is no, even if worldwide it is a commanding leader. If a system is big in Japan AND elsewhere they may even only make it on that system, like Square tried with DQX. But you need a Japanese presence to get the support of key developers like Square, Konami, Capcom, Namco and others. That's why it's important.

Those 13 are mostly the americas and Europe.

Maybe some day everywhere else.  We'll see.

So it's going to be like this gen when they released it officially on my country 5 years later. If that is going to be the case then they shouldn't even bother.

Not sure which countyr you are in, but if they are truely having problems with language support in more that 13 countries, you are probably better to quit waiting now.

Metal Gear Solid 5, Final Fantasy XV and Kingdom Hearts 3 are all confirmed for PS4, so it's not like they're going to lose Japanese support. The sequels to these games will probably remain on the same system.

I'm from Argentina... weird thing is the PS4 is releasing on launch on my country. It is kinda weird as our country is often ignored when it comes to gaming.

I have no problem though, I could get one outside as the Xbox One is region free.

The thing is, in the US both Microsoft and Nintendo saw major growth, with Sony only seeing a modest loss.

Sony and Microsoft combined acount right now for more than the total number of PS2's sold last generation, and the Wii's numbers exceed the combined Xbox and Gamecube numbers. 

Effectively, home console sales are stagnent in Japan.  Where as both Europe and North America have seen expansion and growth.