Why would Sony ever allow a competing game company to use their Blu-Ray technology?
A crazy little thing called cash. :’) Of course, the reason the PS3 is outselling the Xbox is the BluRay; if that advantage is negated, it could be trouble. Development costs for the processor used in the PS3 were very, very high, and it will take years of better sales to get that money back. :’( I’ve read that the next-gen Playstation may not even have a drive in it.
I'm not sure they have a choice. There might be anti-trust issues involved. Or maybe their math is that they'd rather get the license fees for the benefit of establishing the standard.
Honestly, Sony is not a "game company." That would be like saying that Microsoft is a mouse manufacturer. Every XBox owner with a Blu-Ray drive is someone who will buy Blu-Ray discs of Paramount movies.
I don't remember the rights-holders trying to keep a tight grip on cassette, CD, or DVD licensing, because they're much better off taking the licensing fees for the hardware and for every piece of software sold thereafter.