A very interesting article, and there's a lot I can agree with. But...
I am going to 100% promise you that, especially if you are a veteran player or DM, we will include stuff in the next iteration of the game that you will ignore. In fact, I'm going to come out and say that we want you to ignore parts of the game.
I like to draw the analogy between D&D and painting miniatures. Some people mix their own paints from a few basic colors. They have a lot of different brushes, and they spend hours and hours working on a single figure. These folks are veterans who take pride in knowing the craft and pouring time into it. Mixing paints, applying layer after layer of highlights, and bringing a figure to life is all part of the hobby.
Then there are painters like me. I don't want to mix paints. I much prefer buying off the shelf colors in various shades, along with washes and bright shades for shadowing and dry brushing. I paint miniatures because I want cool toys on the table when I play D&D. I'm not gunning for a masterpiece, but instead I want a miniature that looks nice enough from the opposite end of the gaming table. I want direct instructions. If I have to muddle through a hard to assemble figure, I'm likely to become frustrated and do something else.
I think a similar situation exists in D&D. Some players and DMs want to figure stuff out on their own or break down the game and make it suit their style. Other players, either for lack of experience, time, or inclination, want a more direct path to the game.
Okay, that's all fair enough. Except,
I do not want to pay for large amounts of rules text I'm just going to ignore. If you publish another 1,000 page monstrosity of Core Rules, and I'm going to proceed to ignore large parts of the rules... I think I'm better off just ignoring 5e entirely, and going back to ignoring large parts of 3e.
And, yes, I appreciate that squaring that circle may be an impossible task. Other than wishing you good luck, there's not really anything I can say to that.
Adventure Design Guidelines: Stuff such as XP budgets, treasure tables, encounter charts, and so on are there to make it easier to create adventures and build your campaign. If you are a veteran DM, it's quite likely you won't use any of this stuff.
Hmm. I've been DMing for more than 20 years, and you can bet I would use that stuff, at least for a while. Every game is different, and so there's a need to learn the baseline expectations before starting to break the rules in creative ways.
IMO, at least.
Character Roles: This one is bound to be controversial, but I don't think roles belong in D&D as specific, mechanical elements that we design toward. Instead, I think roles are a great tool to help players focus on how they want to play a character.
Yes and no.
In 3e, there were always issues with how the Bard and the Monk fit into the party. Some books even went so far as to say they were an ideal "fifth man", in a game designed for a party of four. The Bard, in particular, was awkward - was it a "jack of all trades", a Wizard-replacement, or a Rogue-replacement? This was never clearly answered, and it meant that the class never really 'fit'.
But as soon as the roles came into being, it became obvious. Of course the Monk was a Martial Striker! Of course the Bard was an Arcane Leader (and, by extension, a
Cleric-replacement)! So, in that regard, the roles were incredibly useful
as a design tool.
That said, I think the roles have probably outlived their usefulness. To a certain extent, it is true that they came to straightjacket players, and it was extremely difficult to play against type - you were generally better off playing a different class, rather than trying to build a "Striker Fighter", or whatever.
Ironically, I'm inclined to think that Mearls has this one backwards - that the roles should be retained as a design
consideration (not goal), but that the roles absolutely should not be mentioned in the print books, even as advice. (Also, while the classes should probably have a primary role, it should be possible to effectively build characters of that class to fill other roles, if desired - so your Fighter
can be a Defender... or he could be a Striker or even a Leader instead.)