UML is very useful to communicate ideas and designs to the rest of your team. It doesn't have to be 100% strict UML. It just has to get the point across. I use http://www.asciiflow.com/ to make simple UML diagrams that I add to my code when it helps clarify the code's structure. So I disagree that you have to "live in the land of too-tight blue ties" to find UML useful.
When you write a text message without proper punctuation or capitalization, do you say that's not English because it doesn't follow strict grammar rules? No. It's less formal English, but it's still English.
