Just, why? Why is there no name?
Coming from an Abrahamic perspective, at a guess, I think it's something to do with Exodus 20:7.
"You shall not misuse the name of the LORD your God, for the LORD will not hold anyone guiltless who misuses his name. (NIV)
It may be because of this, or because of this, or the fact that there are so many Names of God to use (El, Yahweh, Shaddai, etc) to use that just the bog standard word for 'The Divinity' is much better, and may be seen as a way of respect to show you're not casually/disrespectfully using the Name of God.
Although this would not be true for all Abrahamic religions. Many Muslims say the name Allah is the Name of God within Islam (of which I have my doubts due to the fact non-Muslim Arabs use Allah to refer to God, too but this isn't for debate), and I think Allah is used within virtually all, if not all, languages where there are Muslims talking to Muslims (e.g., Muslims may use "God" to explain they're talking about the Divine, but Muslims will more than likely use Allah when talking to another Muslim, no matter what language they're in).
Just my opinion as to why this could be. I'd love to learn about the reasons why though.