To create better, and more useful tickets in hubspots ticketing system. A Date+Time+Timezone picker would be useful for many different ticket types as a ticket property. Date Picker alone is very vague.
I completely understand the value if we were to have it reflect, date+ time + time zone. If you would like for this functionality to exist I would recommend posting this on our HubSpot Ideas Forum. This is where our Product team goes to receive feedback from our customers and also allows for other users to up-vote and comment on your idea.