Hi, I might be the one who made the other thread you are referring to dreambled. My two cents is that if you don't want to activate sneak attack, then attack in a way that wouldn't activate sneak attack. Get off high ground, don't be in stealth, equip a non-ranged or finesse weapon. There is no need for a toggle when the basic implementation of sneak attack, automatic or not, is itself a toggle. The default design of sneak attack should reflect how it's used the vast majority of the time.
This shows a fundamental misunderstanding about how sneak attacks work: It uses your action to sneak attack, so attacking with any other attack that ISN'T a sneak attack uses your ability to sneak attack that round (unless hasted or granted another attack from another source).
The problem is missing with your sneak attack means you don't get sneak attack damage for that round, even if you are using 2 weapons and get your bonus action attack. That's the whole point of 2WF with a Rogue: for extra chances at sneak attack damage during a round. There's also the fact that you don't get a sneak attack for an attack of opportunity, as you would in the P&P version (assuming the other qualifiers were met). That is the scenario where a toggle would come into play. Like you said, the toggle would mostly be ignored, as it is used with the first attack a vast majority of the time. But when it isn't used that way (misses happen A LOT with RNG), it feels like bad game design.
But here's a scenario where you hit with all your attacks and STILL don't want to sneak attack with your first attack: You are using 2WF and fighting multiple enemies. Enemy 1 is next to you and only has a couple of HP left, something you can easily do with 1 + your Dex mod. Enemy 2 isn't within striking distance and has more HP. You would want to use your main hand weapon to make sure the first enemy dies (your offhand weapon only deals weapon damage, no modifier) and then move over to the enemy with more HP and deal sneak attack damage. In this scenario, it's more optimal to deal main hand damage, ensure the enemy dies, and then move to the enemy with more HP and use your sneak attack with one of your bonus actions.
Sneak attacking an enemy with 4 HP when there is an enemy with more HP just feels bad and can actually result in a death (especially since the game ignores action economy when creating challenges)
