My husband and I goo (btw, love the terminology here!) to each other all the time. We have a special "Engrish" that we speak when we talk to each other. For example, we say "herro" instead of "hello," and we take "nappy-naps," eat "runchy-runch," and play with the "kitter-witters," rather than take naps, eat lunch, and play with the cats. Yeah, it's disgustingly silly.

However, I read a statistic recently that said that couples who baby-talk in some form to each other generally have stronger communication skills, have a closer relationship, and are 80% less likely to get a divorce than couples who don't. I'll see if I can find the link to the article and post it here.

As for the rest of your question, our "goo" is pretty important to us, and I know personally that if he stopped speaking to me in our little language, I would feel like I was missing out on something very important or that he was pushing me away. However, I don't find it neccessary to prelude a scene with goo of any sort before I'm ready to sub or dom (I'm a switch). Interesting topic!
-Phan, intrigued