Hi @Emmanuel,
As always, thank you for the detailed info. But I believe you are still not seeing the bigger picture, and remain stuck on functionality over usability. I am well aware of the major differences between v2 and v3, as I have been using v3 since beta. And at no point have I ever suggested loading the entire TW3 CSS library, but I feel that that is how you continue to read it.
Attempting to use ALL 46K+ TW3 utility classes (v2 had 37,080) would be insanity, not to mention completely defeat the purpose of the JIT engine.
BUT…
Expecting your users to MEMORIZE all 46K+ TW3 utility classes is ALSO insanity, which is why practically every other IDE in existence still shows them to you (IntelliSense / auto-completion) even if you aren’t USING them. Or as you put it, “do not exist”. I know, CrAzY right? How can they possibly do that?? It must be the devil’s magic. 
So, kidding aside, just because we would like to SEE the classes that are available to us (as I described in detail a few months ago) doesn’t mean we want to USE them all. It simply means that we are not all savant gods with immeasurable memory. (as much as I would love for that to be the case) 
And to your explanation of why this basic (standard?) functionality doesn’t work for v3, I guess I would be asking myself - SHOULD that be the “normal” for my product? Or should my product be smarter than that? 
But then again, it’s not my product.
Here is a great example of the devil’s magic in action - https://devtoolsfortailwind.com
I really hope this clears things up a bit! And as always, I’m not trying to be HARD on you guys! I’m just trying to get a little love for us NON-WordDepressed users. 