Right now for 2024, every class gets all simple weapons, and they should and it's easier for everyone than to track those few weapons for arcane casters.
Shield are oldest and most simple form of protection or armor, if you can call them armor as they are actively used with your hands.
They are more a part of the weapon set. With spear probably the oldest weapon set in history.
They also affect what weapons you can use, as they (usually) prohibit 2Handed weapons or dual wielding, reducing your damage for added protection.
There is no trade off for armor in damage department, you just get more protection.
With shields available to all, all characters can have options to have:
2Handed option,
Dual wield,
1Handed + shield
both with melee or ranged option.
martial characters can still pick styles, feats and maneuvers that can better utilize shields and set them aside from non-martials.
(as option, it can be added that shields require min STR of 10 or 12 to not suffer penalties, both to speed and attack.) this would discourage STR dumping if you wanted to use shields.