I would chalk that up to a gameplay and story segregation thing, really. Larian would be rightfully reamed for having an encounter like the tavern siege without offering you some way to fully restore your resources beforehand.
If segregation of gameplay and story causes strange disruptions of immersion, then I would call it bad design. Just like sending things to camp and teleportation from everywhere in BG3. If it is not possible to do away with such goofy gameplay mechanics, then at least provide an in-game explanation that is not too hard to believe.
In case of the tavern defence fight, just having the warning to be prepared and the messenger would have been enough. The enemy waiting for you to become fully rested is plain silly. If you were to arrive at the scene with the assault already underway, or just beginning, the thrill would be much greater. And if you came underprepared: shame on you for not listening to warnings.
