I have an 8 year old grandson who loves to take baths. I have the WH set to 140 dF and I installed a tempering valve and set it to 115 dF heater output to prevent scalding. No more issues with running out if hot water.
Yes , adults should be smart enough to test water before getting in but children can't be trusted.
Besides, our dog will jump into the tub if she hears it running, as she loves it.