Great games ? No, I don't know many games, I know wc3 and few more. Great applications? yes. Mapple 11 (per example) is an advanced math simulator and it's all in java. My point is, OOP is something Galaxy should have. This way it would not fall into some of the problems JASS has.
There is a chance I am not understanding the full content of this sentence, but with the experience I have, I know that OOP makes the creation of any programs easier and faster. With OOP (I am assuming Java as example) you spend more time planning the structure of the core and how it will interact, when it comes to code it is a lot faster. This way you can solve problems even before they exist. This is how my university teaches me and I have done many projects using this paradigm (I love OOP xD ).
As for efficiency, I am not sure so I won't comment.
What do you think the point of vJAss is? Why do you think Vex created Libraries, modules and structs ? OOP DOES help people reducing duplicated code, thus making it easier to sustain in the future.
EDIT EDIT EDIT
I've seen the movies. To be honest, You can do many those things with the wc3 engine. Sure they will be different, but it's possible. I've seen amazing single player 3D arcade shooting games with wc3 as well... and they were made in GUI (which made me even more impressed....)
I liked the last demo of the movie with the ship flying around and killing protoss airplanes, and I know how I can replicate it... Maybe an idea later if I have time xDStill, my main opinion is maintained.