Back in the AD&D era, there were indeed some additional difficulties. However, I do not believe that these peripheral things are where the "balance" is to be found, for various reasons. If your goal is to achieve balance between casters and noncasters, I believe it is best to look forward, and not backward.
I'll go from last to first.
• "Spell Memorization Time" is not a restriction for wizards. Instead, it is a bother for the entire party, because they will simply wait for him to finish. A wizard is part of the party, and it is poor strategy (and no fun) to have part of the party sit out the action. Even if they have to wait days,
they will wait.
• For all the power of wild shape and animal companions, druids are not tier 1 for those things. They are tier 1 because they are full spellcasters with access to a wide list. Wild Shape is basically just another spell, and animal companion another fighter in the party.
• When I play a wizard in AD&D and I need to carry my spellbook, I buy a mule. The size and weight of the spellbook are the least of anyone's worries. As for the WBL thing, WBL is for the whole party. PCs distribute the treasure evenly (it would be odd to give the wizard less), so counting spellbooks against WBL does not increase party balance, and will probably make it worse because the fighters cannot afford to buy the magic items they need.
• Codes of conduct are roleplaying guides. Played properly, it means that a cleric needs to act like a cleric, which isn't hard to do. Played improperly, it is the DM looking for an excuse to remove a party member, which will satisfy exactly no-one, including the nonmagical party members.
• The number of spells available is a function of book selection; there are few spells to choose from in core-only 3.5 for example, and that does not make core 3.5 balanced.
Finally, the limited spells known. This is the one that has a real effect, though it can be gotten around in AD&D by researching new spells (spells you invent yourself do not count towards the cap). In d20, however, you need look no further than tier 2 classes if you want something similar: they too have a limited number of spells per level. If you remove tier 1, the argument merely turns into "Sorcerers are uber broken" instead of wizards, because you do not actually need that many spells to cause the balance hissifits.
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Where am I going with all this? The answer is that if you want balance between "
BatmanDOCTOR DOOM, CoDzilla and mortals" then the way to do it is directly dealing with what spells can do, compared to what nonmagic classes can do. The most effective way to balance is to look to 4e, not 2e. In 4e, spells simply aren't as good any more, and run on the same system as the mortals. To give a 3.5 example, the warlock is rated the same as the rogue, despite having unlimited magic per day, no need to deal with spellbooks or components, no code of conduct, and no prep time!
Why? Because the warlock's magic isn't all that great.The root of the spellcaster's power is his spells. Changing everything but the spells themselves is missing the point.