Trig functions in JOML returning doubles - why not floats?

[WeBeJammin]

I know this is basic, but I thought I should ask the question to see if I was missing something.

From what I've read, OpenGL and GPU programming are tuned to use floats. But all the default trigonometry functions in the suggested JOML add-on return doubles. Wouldn't it be better to return floats?

[Cornix]

Why would it be better?
What do you believe would be improved?
Casting doubles to floats is trivial.