Granted Go doesn't have as many libraries as the more established languages, but to say there aren't many and there's "nothing to learn besides the language" is just flat out wrong.
Just for starters there's http://code.google.com/p/go-wiki/wiki/Projects
And there's probably more to a lack of an ORM other than "Go is immature." It's a fairly common opinion among the Go community that ORMs are not worth their complexity. I tend to share that opinion myself, after having worked with a few in a couple different languages.
As to only the lack of ORM would make Go immature? Honestly I don't know. There are tons of software written in JavaScript; do they make JavaScript mature? Hell no.
In a multi-paradigm language you wouldn't be tied to using an ORM but you should still use something that provides some kind of anti-corrupt support. In an OO language you can have nothing but objects so there is nothing else your database library can return. It may as well return objects that represent the records rather than, say a list of strings.
I know that I've used Hibernate for years. I've used it with DTOs. I know that it does provide a certain benefit for simple reads and writes. Unfortunately, Hibernate was designed to work in a disconnected manner like the Web. As a result you get into complications of session management. This is just one example of Hibernate maintenance costs.
Now I use Spring JDBC. This removes the noise of the checked exceptions, connection management, transactions, just like Hibernate. But I write simple or complex SQL in one place and map in and out contently.
In C# the session management is no big deal: you access everything via the Repository pattern, turn on trait injection and just make sure any repository method that will need a session has a transaction attribute. If you need to do a series of read/writes in one transaction you throw that whole method into the repository class and put a transaction trait on that method.
In any solution you come up with you'll either need a repository that handles sessions and so on, or you'll have to explicitly connect to the db every time you need it. Either case will be more work than what I've done with this solution.
Really? Because we managed to get just fine without one for decades...