Not getting hit in the first place is the primary defense in 6e. Yes, there's a paradigm shift: in 5e you can fairly expect to shrug off attacks entirely. In 6e you can't fairly expect that. It's an inherent change to the metagame that in 6e if you get shot, you probably WILL get hurt somewhat.
You were still wrong about armor protecting against toxins. Besides that, not getting hit in the first place is the primary defense in every edition of Shadowrun. It's just that getting hit is inevitable for all but the most Black Trenchcoat of players, so you need your armor to provide soak dice for when you do get hit.
But you don't know that there's NO way to augment soak rolls. You only know that armor doesn't augment soak rolls.
Pattern recognition says either there won't be any way to get more soak dice, or they'll be very costly to obtain. What's more, soak dice against toxins and specific element types are going to be even more expensive, if they're even a thing. Specialized protection is more difficult to obtain than normal protection; if soak dice against bullets and knives are no longer a dime a dozen, then what kind of price can we expect to pay for soak dice against toxins, or against specific elemental damage?
If you're not directly familiar with why the toxin messed the SCN actual play party up, let me recap: toxin damage isn't "one and done" in 6e. You keep taking the damage over and over. Until you don't. The "damage over time" effect without a good way to stop it is what wrecked them. If memory serves, they only took like 2 boxes of damage from rat bites.
So getting hit with an injection vector toxin is worse than it was before, and now there's no way to protect yourself from an injection vector toxin except "just don't get hit lol". Well, now it makes sense that Strength no longer contributes to melee damage, because no one is going to use a melee weapon other than syringes full of Narcoject ever again.