@zombi
I mean, there are at least several alternative machines, and customers have fredom of choise in game console market.
On the other hand, for personal computing %90 percent of machines are IBM competable PCs. It is nearly impossible to produce an alternative machine and make profit.
That doesn't mean that game console market would be any less competitive. On PC market they at least don't sell the HW with losses, but on game console market they do (the idea being that the sold games will balance the situation, and eventually generate profit, see XBOX).
It is much harder to make new game console than to make new PC design (be it regular PC or otherwise). You need something like resources of Microsoft and billions to back the program to make it happen... For the first 4 years, Microsoft made 4 billion USD losses, but eventually XBOX turned profitable. Now, I'd claim that you don't need to take 4 billion & 4 year losses with regular PC hardware or even some custom arch to make it even.
The game console market is VERY hard to get into, it's basically ruled by the three big ones now: Sony, Nintendo and Microsoft.
So again:
Why? I think it's a good idea. Because competition in game consol market is not as hard as personel computer market.
Because you don't have the 4 billion USD. Because you don't have the resources it takes.