I agree that just because you can quilt densely doesn't mean it's a good thing for all quilts. As in Scissor Queen's comment, dense quilting has served the purpose of holding it all together for years & years. Now, since batting has improved, we have more options -- although keeping it even is still a goal. I like to consider each quilt individually, & longarm quilt it for it's purpose. For instance, baby quilts that are actually going to be used are nice left cuddly! The batting chosen makes a huge difference, too. Whenever possible, I go for the non-shrinking, QD wool batting -- so soft & still holds together if some spaces are a little farther apart.
The beauty of quilting is that it allows an individual to make so many unique, creative choices, with not many rules to worry about (as long as it holds together nicely)!