We can thank Rutan and some of the other kit plane companies.
If it wasn’t for them and their light fast designes we would still be dealing with aluminum and rivit brains.
Actually, we should thank Lockheed and McDonnell-Douglas more than Burt Rutan for making composite airplanes possible for commercial airliners. Boeing just borrowed a lot of the research done on composite structures used on military aircraft and applied it to the 787. (The F-16 Fighting Falcon and the F-18 Hornet were among the first aircraft to use composites in a number of critical components to keep weight down.)
In fact you can thank NASA and most of of the aerospace industry as well - today's composites, your digital camera, and lots of other goodies have been in the works for decades before you saw a sign of them.
What Boeing has done is to skip the "oh dear, it's going to be really hard to be the first.." stage and decide that Rutan and others have done enough ground work to make scaling up into commercial aircraft feasible.