Why? AFAICS, SPDY is open and available for everyone who wants to implement it.
What's so bad about companies making it open, free and open source, thus contributing to a better Internet experience for everyone? No one limited SPDY to Google sites - Microsoft and Yahoo are free to implement it for their servers and enjoy browsing speedups with Chrome and (soon) Firefox 11.
Yes. Apache already has mod_spdy and nginx has plans to implement it. Browsers fallback to regular http if the server doesn't speak spdy. There are no disadvantages for you.
I think programmers have achieved harder tasks than detecting which protocol the server speaks and speaking its language, starting with the most optimal protocol and falling back to simpler and more common ones.
What's so bad about companies making it open, free and open source, thus contributing to a better Internet experience for everyone? No one limited SPDY to Google sites - Microsoft and Yahoo are free to implement it for their servers and enjoy browsing speedups with Chrome and (soon) Firefox 11.