AD&D or 2nd edition spellcasters were absurdly powerful at high levels. That has nothing to do with Baldur's Gate 1&2 devs but everything to do with D&D.
It's more relevant to discuss Larian and their design choices and homebrew rules in this game.
Did improved alacrity - which removed the one spell per round limit - exist in 2nd edition pnp, or was it something that the devs made up? What about the way illusion clones worked? Or spell resistance?
A lot of the power of arcane spellcasters comes from deliberate design by BG devs (such as wand recharging), and also from the exploits and bugs they never bothered fixing.
