Fun fact 1: The game is in Early Access.
Fun fact 2: You cannot normally access level 5.
Fun fact 3: A shitton of class features and systems are not yet implemented, never mind working properly.
By all means, feel free to offer suggestions to Larian about how you would like to see the game work. That's fine and good. But perhaps take fun facts 1-3 into consideration before jumping to conclusions. There is perhaps a connection between fun facts 1, 2, and 3.
Fun fact 1 : You cannot have a mage hand and a familiar at the same time
Fun fact 2 : Larian already did everything that they could to destroy casters in BG3. HP bloat, spell nerfs, ultra limited max level...
Fun fact 3 : Larian never had a game with good necromancy
Larian has a LOT of resources. If they din't allowed us to see the tier 3+ spells is cuz they are debating if they will """balance""" or not(read : Balance = Ruin and force everyone who wanna a more P&P experience to use a mod like spell fixes for nwn2)