Gradients need to be controlled if they are the background for text.
The gradient in the example on the left is good: it consists of dark to dark and, therefore, the light text is clear and readable. The examples in the middle and on the right are not great. The gradients are both dark and light, so whether you put light text or dark text over them, part of the text loses clarity. The light text in the middle example loses clarity over the light portion of the gradient. The dark text in the right-hand example loses clarity over the dark portion of the gradient. Never lose clarity for the sake of design. Be careful how you choose your gradients when text is involved.