I'm paraphrasing/selecting representative samples of your post; I think this is a fair summary?
Originally Posted by Chief_Jericho
... Spells are disinteresting, boring, they feel like I'm chucking a wet lettuce rather than a fireball and that's a moot point since the majority of the time I miss anyway, or I'm put to sleep, or I'm instantly killed by a single spell or ability...

DAO and DOS have mana/cooldown systems but BG3 has a longresting spellcasting system. BG3 spells feel both weaker and more limited than spells in DAO/DOS.

Arcane recovery ...why would I bother using that when a full rest will regenerate all my spells? I'm essentially saying that you need the ability to regenerate the spells in combat, not just out of combat. Spellcasting - and I don't just means Wizards - in this game is not fit for purpose
These things are ~fair criticisms. As others have said, spellcasters are relatively weak at early levels, but get many more spell slots at higher levels (Wizards have ~10 spell slots at level 6, which is more than enough for a single combat). But, being more versatile at later levels doesn't necessarily justify having early levels be un-fun. To this, I reply that low-level spellcasters are at their best when using utility and/or long-lasting spells (buff allies, debuff enemies, escape from melee attackers, mage armor). However, Larian's changes to 5e have made buff/debuff/concentration spells much less useful, turning tactical-utility-spellcasters into inefficient blasters. Particularly the increase to goblin HP has made spells feel less effective even if they hit.

I'd recommend trying to change your perception of (low-level) BG3 spellcasters from DOS/DAO powerhouses to what they are in BG3: cantrip-casters that occasionally use the more powerful spell, usually to finish off an enemy, buff/debuff, deal AoE, or escape from danger. In PnP 5e, low-level spellcasters cast 1 or 2 leveled spells per combat. Long-lasting spells are often the better choice, that is if you can retain concentration. Also, make use of scrolls! These will significantly extend your wizard's ability to be useful in combat.

Arcane Recovery: Yes that is a good question. This is an effect of Larian's decision to allow unlimited resting, which makes short-rest recharging abilities basically worthless. It is unclear if Larian is going to make further changes to the system. Currently, the only reason to short rest/limit your long rests is for roleplaying/immersion's sake. But doing this you're penalized by missing out on camp cutscenes.