Most dogs don't drink water at night anyway, so there isn't an issue. Dogs are like humans, they drink mindlessly too. I've seen my dog get up, go to see the other animals, lay down a bit, walk around more, sniff the table, go sniff her food and water, walk away, come back a minute later and drink for a second and walk away.
In the case of children, they often ask for water to stall having to go to bed, telling them no is not cruelty. Also, if you know the child is peeing the bed at night because they don't have an alarm in their head to wake up and it's giving themselves a rash, then taking away water an hour before bed is not cruel, it's preventing a problem.