Hmmm... I wonder how many players share your outlook? (That's not rhetorical btw, I think I'll set up a poll.)
This is tricky. I'm having a hard time imagining a solution that would satisfy both your preference and other play styles.
Most people I knew house-ruled their way around at least some of those restrictions, because they didn't like them, which obviously tended to create balance issues. As such, my experience is with those who like powerful wizards, but don't want to deal with all of the balancing restrictions. Clearly, that doesn't apply to you.
Going back to this style without giving players a means to opt-out (other than simply not playing a wizard) would probably alienate a lot of people, which is rather antithetical for the "unifying edition". Of course, abandoning it entirely sounds like it will alienate anyone who shares your views.
Those houserules, as you say, created all source of balance issues, and by becoming core in 3e created all kind of problems, among them the 15 minute day and the power discrepancy between the wizard and fighter.
Let me address each of them briefly.
-Wizards had the highest xp requirements of any class.
Being a wizard is HARD. Otherwise, there'd be a ton of wizards, and the entire milieu changes. It changes from a psuedo-medieval world to the world of Harry Potter.
-Wizard saving throws, most notably against death magic, sucked.
Yes, but most death magic is from a spell, so they have the best in the game at those. Death magic also falls under the same heading as poison and paralyzation, wizards, being frail and not very athletic are not very good at overcoming poison and lack the strength to fight off paralyzation. Their saves represent a wizard being studied in the arts, they know just how to react against magic, but not so much against physical stuff. So, why can't I play an athletic wizard? Because AD&D is about archetypes. Conan the librarian is not an archetype.
-Their "Thac0" was only 13 at level 20. (Their ability to hit sucked.)
Rightly so, they are magic users, not fighters. If they learn how to fight very well, their study of magic will suffer. There's only so much time in the day, after all. Note that at 1st level, they are every bit as good at hitting things as a fighter. That's why the exp requirement is so high at lower levels, then gradually gets easier.
Removing this mechanic was 3es biggest mistake. It made wizards into gods. There's no easy way to interrupt a spell, it requires readying a partial action. You only have one shot, and that's your round. Inefficient and more importantly, boring. Spells must have some sort of casting time.-Any damage would automatically waste the spell. Since actions were declared before initiative was rolled, and initiative was rolled every round, you never knew how many attacks you might take before finishing your spell.
-Wizards had a measly average of 34.5 hp at level 20. Note that this means he could be killed by an average 20d6 fireball, regardless of whether he makes the saving throw or not. He can kill himself quite easily.
Yes. As noted above, if you study 16 hours a day, you will never be a professional wrestler. It keeps the wizard within his archetype. He doesn't wade into battle unless there's no other alternative. And why should he? He's not a fighter.
-They had quite severe limits on the number of spells they could learn (from 6 to 18 spells, barring a 19 Int), and had only a percentage chance that they could ever learn a given spell (from 35% to 85%, barring a 19 Int). Since stats were rolled in those days, it wasn't unusual to see a 16 Int Wizard (can only learn 11 spells per spell level, and only has a 65% chance to learn that given spell, and can never cast 9th level spells). If you failed your check to learn the spell, you could never learn that spell (barring not meeting you minimum number of spells limit). Envision yourself as a fire mage but rolled a 89 for fireball? Sucks to be you; you'll never be able to cast fireball.
Without the chance to learn spell mechanic, most wizard will have the exact same spell list. Yeah, you might have a couple different spells for flavor, but seriously, what wizard doesn't know magic missile? It provides for variance among wizards, yet doesn't make you useless if you fail the roll. For example, here's the list of spells my 5th level mu CAN"T cast: Identify, Wizard Eye, Web, Melf's Acid Arrow, Tasha's Uncontrollable Hideous Laughter, Invisibility, Hold Person, Fireball, Lightning Bolt, Fly, Melf's Minute Meteors. Would you call him useless? You'd be mistaken. He has sleep, magic missile, charm person, mirror image, stinking cloud, phantasmal force, dispel magic, monster summoning I, Invisibility 10' radius, and several utility spells. He gets along just fine.
Nor should they. Armor is for lesser mortals who can't warp the fabric of reality. It doesn't fit the archetype.-They couldn't wear armor at all.
-They couldn't circumvent vocal, somatic, or material component requirements by any means (no Still Spell, etc.).
Again, this is both thematic and a balancing factor. Tie a wizard up and he can't fry you in your sleep.
Many spells had significant drawbacks. Some had expensive material components (5,000 gp to cast shapechange), while other spells had serious drawbacks, such as polymorph other requiring a system shock roll just to survive it and another roll for the mind to remain intact (useful against enemies, but potentially disasterous if cast upon a party member).
These are more of the balancing factors of magic. Magic is a resource to be hoarded, used when necessary, not thrown at every simple problem in your path. When magic becomes spammable, at will, it is no longer special and no longer magic. Polymorph becomes a high risk/high reward spell, not a standard procedure.
-Spell resistance was a flat percentage, unlike 3e. Many high level creatures were practically impervious to magical attack. And let's not forget that you were completely boned in an anti-magic field.
Not all tools work on all jobs. Sometimes you have to improvise. Besides, isn't that the point of an anti-magic field?
All of these factors both make playing a magic user challenging and fun, and keep him from overshadowing the rest of the party. Now, I'm not saying it should be ported whole cloth into 5e, after all, then it would just be a clone of 1e. I am saying, if it ain't broke don't fix it. Keep the thematic elements of 1e magic, keep the strangeness of magic, keep drawbacks. I wouldn't mind seeing a few more spells per day at lower levels, but from about 5th level on, 1e is just about perfect. Enough to do the job, but not enough that you just spam the left mouse button.