Utility classes.. Good or Bad?

Question

I have been reading that creating dependencies by using static classes/singletons in code, is bad form, and creates problems ie. tight coupling, and unit testing.

I

Answer 1

You could always create an interface and use that with dependency injection with instances of classes that implement that interface instead of static classes.

The question becomes, is it really worth the effort? In some systems, the answer in yes, but in others, especially smaller ones, the answer is probably no.