I don't see any depleting part : have a dialog, go to your room to replenish the bar, come back for another dialog, come back to your room, ...
Maybe to adapt the game to your will you may forbid replenishing the bar access for 1 hour or 1 day or one month after using it
You're only considering what the game is
now.
Keep in mind that it's still
in development. And Baal has planned ahead. So some features that are in the game sometimes don't make much sense until a later version when he gets the chance to add in the reason for that feature.
The best current example of what he means by 'depleting resource' would be the Friday night party.
You're going to be there for 4 game hours without any ability to reload your hotbar.
So it's a good idea to plan ahead for what you want to get done on the night of the party and load the bar with what you need for the night.
The bar is another example, since it takes an hour to get there. It's best to load up the hotbar with 3 conversations worth of topics you want to use on Gina or Lisa. Instead of losing a game hour to go back home to reload.
Downtown is still in development, but an hour there and an hour back, so it'll become the same situation as the bar as it's expanded. You'll want to plan ahead for your trip.