Our 4 small dogs sleep in a large crate all night - no problems. They all trot in there quite happily at bedtime. We've also got a large one in the back of the car, but only leave them there as short a time as possible, and that's really only for safety, while I'm driving
I think that as long as they're not used excessively, or as a punishment, they're fine, but owners should think about why they're using a crate and whether there is a better alternative. (For example, if the dog's chewing, give it a bone!)
Just my opinion !