It is interesting to read this thread after so many complaining that Larian are not true to D&D or Baldur's Gate and have simply created another D:OS.

The issue with resting to regain spell slots is heavily integral to the D&D mechanics. It has been that way from day one and is the way the game works. There have been plenty of calls over the decades to change to a different spellcasting system, but the legacy Vancian one-shot system is still part of the game rules and spellcaster design is balanced to reflect that. Think yourself lucky that D&D5 has moved on from the previous editions where each prepared individual spell was gone when you cast it; at least D&D5 uses spell slots to cast any of your prepared spells (which used to be the preserve of Sorcerers and Oracle). If you'd already cast your two prepared slots of Magic Missile and encountered another enemy, you'd better hope he could be defeated using Identify or your Invisible Servant.

The resting mechanic is as much an issue in the tabletop D&D5 game as with the computer version. In a GM-led game, the GM may restrict the periods between resting to stop 'long-rest-spamming', but the rules don't really make that distinction so far as I can see. So, in short, Larian have largely replicated the rules and mechanics of D&D5 for this game, and any fault in those should be directed at the D&D5 system itself rather than the BG3 game developers.

(Just for clarity, the AD&D/D&D game system is not my favourite, mainly due to its clunky character development restriction and 'artificiality'; the above complaints being examples of this).