re: Just once....
Larry, I think we can blame Colonel Shorty Powers for the low-key statements at NASA launches. He was the first NASA public affairs officer and he was known for his laconic pronouncements during the liftoffs of Al Shepherd and the rest of the Mercury flights. He set the tone that has been continued to this day. I remember how enamored the news media was with his calm liftoff comments.
I do think that the announcer of STS114 did let a little emotion get into his voice when he practically hollered 3 engines up and running as the shuttle came to life. That was a bit better than the past.