After listening to the Sage Advice video I have come around on it.
I think both taking a bonus action after its requirement and not splitting up actions is the way to go because it makes things simpler, especially the latter.
Totally not the case, from a simple grammatical perspective. "If you take the Attack action on your turn" is not the same as "after you take the attack action," nor is it the same as "once you have completed the attack action in its entirety," nor is it in any other way past tense. "You take" is present tense, as opposed to "you took" or "you have taken."
Similarly, "you can use a bonus action" is also present tense, and not future tense. It is not "you will be able to" or "you can then take" or anything of the sort.
I will agree that in most cases, an "if a, then b" structure suggests that "a" come first, but certainly not all the time. In this instance, it seems most reasonable to read "a" and "b" as happening at the same time. Take, for example, the wording of the Extra Attack feature, "whenever you take the Attack action on your turn." That's still an "if a then b" logic structure, but the word "whenever" implies concurrence. In fact, that is exactly how I've been reading the feat all along, reading the "If" the same as a "When," so that the Shield Master can choose to have an Extra Extra Attack that can only be used for the Shove and precludes other bonus actions on his turn, but otherwise (especially for timing) works the same as the Extra Attack. Slice, shove, slice... shove, slice, slice... slice, slice, shove... no difference.
This whole concept that the Attack Action is the same as the attack you make "with this action" (note that "with this action" also doesn't really carry timing constraints) is new, and the fact that Jeremy has been beating that drum a lot in the past few weeks doesn't change the fact that it's new. His insistence that declarations don't count opens other issues, as well. Take, for example, the Sanctuary spell. "Until the spell ends, any creature who targets the warded creature with an attack or a harmful spell must first make a Wisdom saving throw." If you fail the saving throw and don't choose another target, then you don't make an attack and therefore under the new Crawford interpretation you have not taken the Attack Action, and you're free to Dash, Dodge, Cast a Spell, etc.
If I take a quarter off of the shelf, it has been taken off of the shelf. If I take someone's advice, I have taken that advice. If I take a look at something, that look has been taken. If I take a selfie, the picture is done. At no time is any action that I take in the process of happening. Present tense would be taking. Can you give an example of take that is in process rather than already having happened?
...
That's not true at all. Specific beats general and the game explicitly says spells are specific rules. Sanctuary works just fine with both Crawford's ruling AND with not having the ability to switch to a dash or other action.
If you take a quarter off the shelf, you can pick it up with your left or right hand. If you take someone's advice, you can still pretend to be ignoring her. If you take a look at something, you can squint. If you take a selfie, you can use a special filter to make yourself look pretty.
With regard to Sanctuary, specific and general doesn't enter into the equation. If you fail the saving throw and you do not choose another target, you have not made an attack, period. You've not even targeted the protected creature. You've declared the attack, but not attacked, and therefore (per the new Crawford interpretation) you have not taken the Attack Action and you can do something else instead.
Also in the PHB under combat, making an attack.
"If there's ever any question whether something you're doing counts as an attack, the rule is simple: if you're making an attack roll, you're making an attack."