When you have something like a five digit pincode that for aestethical purpose consists out of five actual inputs (for spacing and border for example), it's quite okay to use centered text inside the input.
The problem is with the way the human eye scans a form.
In a vertical form the eye shoots to the start of every new line. Inputs with centered text are therefor harder to scan. In a serious form this could harm conversion.
So yes, I think you can use centered text in inputs and forms, but only on those rare occassions where it suits the design.