This is a pretty good summary:
Points 1 and 3 were the ones I was more concerned with when I made the poll.
For points 2 and 4 I rely more on the players than the rule-set. Creative backstories and such will make a good start for point 2, and the whole process of the actual gameplay itself leads to point 4 IMO.
Except that the locked in class and level system of D&D massively inhibits non-linear character growth compared to other RPGs.
To give an example from the last campaign I was a player in, it was a SF game with us starting off as poor merchant traders. My character started off as a fairly sneaky rogue type who made his official living as the ship's engineer. Not formally trained he was good at jury rigging with duct tape and string and competent enough to be an engineer on a cheap tramp freighter but nothing special (as well as being good at stealth, lockpicking, hacking, and the rest of the sneaky rogue set).
However as the campaign progressed we got our hands on Old One technology and he stepped up as the ship's engineer. His skills were called on both under fire and to fix ships and ship parts that no one had ever heard of because it had been tens of thousands of years since this tech had been seen openly. He never got any better at the stealth and infiltration I expected him to be used for (we had several stealthy people and his normal role in stealth operations was sabotage and computer hacking) but because he grew from where I spent the skill points and I spent them on what I was doing he became one of the best engineers in the galaxy thanks to his access to parts and problems no one else was using or facing.
Because we were playing a skill based game (Storyteller rules) his focus was able to shift organically rather than either changing my entire class or levelling up in lockstep in the rogue class. So he turned organically from a rogue who made his living with duct tape and string to an expert engineer who was well acquainted with the seedier side of engineering (and became a slightly more dangerous fighter in passing). This worked well and was character development - but because in D&D 5e you've made almost all your choices by level 3 you almost can't get the same sort of story in 5e and if you do the rules fight you all the way.
Edit: And you say "Creative backstories and such will make a good start for point 2" - which is true. They make a good start. But if "a good start" is all we want then we might as well dump backgrounds and just ask for creative backstories. For that matter we might as well dump skills entirely, and most spells. What we want to do is work with and be able to both inspire and build off creative backstories and such - and this goes for just about all of tabletop roleplaying.
If a player focuses too much of their character's growth on their features they gain or can choose from for point 4, your character is really just a bunch of features and numbers on a sheet.
And that might be relevant - but given how rigid the character levelling process is in 5e it's like saying "if someone gets too hot they will faint and eventually die" to argue against turning the heat on in sub zero temperatures with bad insulation. Sure, it's a
theoretical worry, but it's a very distant one from where 5e is.
LOL those are the classes I dislike the most (with bards being a close third), but that doesn't surprise me given our differences in the past.
So, what, precisely, do you find appealing about those classes for point 4, then??? (Honestly curious here.)
@TwoSix nailed it. With both classes you pick class abilities distinct to that class and two e.g. Infernal Warlocks can be and grow very differently thanks to different Pact Boons and Invocations rather than having all the same abilities because they picked the same subclass. Your spells are
also a character defining choice and might have no overlap between two characters of the same subclass rather than their choice in spells being a matter of what they decided when they woke up that morning.