Different people have different view on this. I have never been one for spaying/neutering rats just automatically the way you would a puppy or kitten because they are awfully small with awfully delicate respiratory systems and there's always a risk with anesthesia as well as a risk with any surgical procedure.
However, it certainly can curb hormonal behavior in boys and can prevent health problems in girls, particularly health problems associated with over breeding or with hormonally induced tumors. I think though if I had a happy healthy well adjusted rattie, I probably wouldn't do it.
On the other hand if you have a rattie that has been overbred before coming to you, has had reproductive issues, or begins developing tumors, it can be an absolute life saver!
One thing that I did hear about if you want ratties that live longer, is ordering them through certain labratories. Many labratories breed rats in sterile conditions to be myco free and free of certain genetic diseases such as tumors etc because they don't want any confusion between the effects of whatever drug or disease they are studying in the rats and any conditions the rat already had. Many of these labs sell pet rats to the public. Of course this would only work if you didn't have any other rats in your house at the time because of course as soon as they interacted with other rats they'd be introduced to myco. But it would be an idea if you didn't currently have rats. My only issue with that and the reason I haven't done it, is that the same labs specifically breed rats with diseases, and mistreat them in a variety of ways, so would i really want to buy something from them and financially support the rattie death machine? It's a somewhat gray ethical issue.