So this is the thing about encounter building, encounter frequency and the rests.
The game was originally designed to have 6-8 combat encounters between long rests and two to three short rests between these long rests. This is why casters have a ton of spell slots, this is why some classes refresh their stuff on long rests and some refresh them on short.
And common complaints about 5e were that combats are easy and that full casters are overpowered. And this was in big part due people not actually running the suggested number of encounters between the rests, which is understandable, as that it just doesn't fit the narrative pacing a lot of people want. That much combat daily might make sense in clearing some old school mega dungeons, but that just isn't how a lot of people play these days. Like I would consider my game to feature quite a lot of combat, but it is actually rare there to be more than one fight per in world day.
I don't see that any of this has changed. But they seem to have removed both the suggestion for the number of combats, so the GMs don't even know what the assumption are, and the only tool for altering this pacing whilst maintaining the balance which is altering the rest lengths. So a lot of new people will end up having these problems, but they will lack both the information to help them understand why this is and the tools for fixing it. I don't think this is good.
As for hypothetical book of options, a full dedicated GMs toolbox, yes that would be a dream come true, but at the moment I have no reason to believe that such a thing is coming.