The +2 AC from the shield is an abstraction, but it is not abstracting "has a shield", it is abstracting "wields a shield in their hand and is actively using the shield to defend with".
I agree with most of your points, except:
I dislike floating ability scores for all races. I enjoy that per PHB races have their identities. Your example of Drow being weaker than High Elf doesn't really work. Drows get bigger range on their Darkvision and additionally Faerie Fire/lr at lvl 3. There are classes/builds that will benefit from those a lot more than a single cantrip.
Additionally both Variant Human and Hexblade are over-adjustments on weaknesses of base Human and Pact of the Blade respectively. I would rather see Larian improving Pact of the Blade a bit and give humans something that is not as game-changing as an early feat.
By definition, you would not have to use floating ability scores. They would start out as the default, and you could choose to swap them, or leave the ASI's where they were. It would not affect you, but it would allow for say, a Halfling Wizard to exist without being mechanically penalized. That would allow more players to play how they want while not affecting players who wanted to keep the default.
(Note: I forget if the Mountain Dwarf with its +2 STR/+2 CON exists in BG 3 (I think it doesn't), but obviously for balance reasons, attempting to floating those would not get you a second +2.)
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Improving Pact of the Blade would not be a bad idea, but that does not preclude also including Hexblade, or a slightly adjusted Hexblade.
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If the Feat granted by Variant Human is too powerful, a possible adjustment for Variant Human which does not grant a feat could be something like "Humans gain proficiency in two addition skills of their choice, and one of them can be with Expertise (double proficiency bonus)." That would not give them a special ability like Darkvision which real humans don't have, but it would grant them an unique and worthwhile bonus.
