Upfront: I really like 5e.
I'm inclined to say the "true issues" of D&D are as follows:
(1) It Doesn't Do Its Core Gameplay Well
D&D tries to be too many things to too many different player bases without adequately supporting any of them. (The italicised part of the prior sentence is, I think, the rub.) It makes sense for the market leading game, one with a long history of supporting some of the biggest strains of gameplay - "classic/old-school", "trad/adventure path", and "neo-trad/PC-story-driven" - to want to be able to accommodate all those styles, and fair enough! But it does so in a very unfocused and wishy-washy way, such that it doesn't robustly support any of these styles of play; what's more, it does so in a way that each of the different strains/styles of play interferes with the others.
For instance, if you want to play in survival mode, such that light, time, food, and encumbrance matter, D&D gets in the way of this: too many ancestries have darkvision, light is a cantrip, the ranger and goodberry make food a non-issue, and so on.
At the same time, if you want to play in a heroic mode, the expected adventuring day (one hour short rests, recovery schedule based on attrition over 4-8 encounters of varying difficulty) gets in your way, and so do all the rules that try to force survival gameplay on you.
If you want to play characters that, by your own standards, are grounded/down-to-Earth/whatever term you feel is appropriate, the way magic works gets in the way.
If you want to play larger-than-life characters (well... all right, if you want to play larger-than-life characters who aren't spellcasters), the way "martial" characters are designed (clearly meant to feel "grounded" over 20 levels - even if they don't feel "grounded" enough to the people who really want "grounded" characters!) interferes with your preferences.
I am sure other examples could be given.
Is there a Solution? I'm not sure, but it seems to me that if D&D were to start from the premise that its core gameplay is to provide a heroic fantastic adventure driven by the player characters and robustly support that, and then look at how it can robustly support older modes of play, it should be possible for it to do a better job of satisfying these disparate groups.
(2) It's Player Base Is Too Divided
This is partly a cause of point (1). The D&D player base is clustered into disparate camps with widely divergent sets of gameplay preferences - divergent to the point where they are often fundamentally at odds with one another.
This might not be a big concern for the D&D design team - unless, of course, the design team consists of factions divided up according to these gameplay preferences that want to see their own preferences prevail rather than have a cohesive vision for how the game can better support multiple playstyles. (The thread about Ben Rigg's presentation on 4e suggests that factionalism is a big problem at WotC, although I don't believe any mention is made of whether such factionalism reflects the broad divisions within the player base as regards playstyle preferences.)
Is there a solution? No, though maybe if D&D the game does a better job on point 1, the divisions in the player base won't matter so much. (Although I shouldn't expect any improvement in discourse.)
(3) The 2014 DMG is a Hot Mess
Plenty has been said on this subject, so I won't say any more, save to say that suffice to say it especially compounds the issues that follow from point (1).
Is there a solution? Trivially, yes. Hopefully WotC has been hard at work behind the scenes working to ensure the 2024 DMG is better laid out and organised. (I don't, however, hold out much hope that it will satisfactorily address the issues that arise from point (1), though it might at least alleviate them to some extent.)
Somewhat of an aside related to the current "subthread"...
Every week, I play a more-or-less strategic-operational level WW2 board game. This game does not have detailed rules for supply where you have to see to your stocks of oil, antimony, coal, steel, rubber, manganese, pork, textiles, etc. etc. etc. to make sure that your armies in the field can actually function. That level of detail is plain and simple out of scope for this game, because so much of the small-scale details are abstracted. Instead, supply is a binary - "are you in supply or aren't you?".
Most (if not all) board games operating on the same scale do something very similar. I'm not familiar with tactical-level WW2 games, but I'm sure they abstract it even further - when all the action is the fighting in Eastern Front Town одиндватри [*], knowing whether the Rhineland coal mines had enough output last quarter is even more out of scope when all you're trying to do is figure out whether your company can seize this town from (or hold it against) the Red Army.
What is more, even if you do have a game that operates exactly on the gameplay scale where it would be "in scope" carefully tracking supply chain inputs and transform them into specific outputs that your armies need to function (and then carefully distributing those outputs with hard decisions about who gets what), no one in their right mind would make a game with that level of detail, because that's not the kind of game people are interested in playing. (I mean, some niche number of people might be... but not enough for Compass Games, Decision Games, and so on to put any effort into making one it seems.)
To my mind, insisting on modern D&D having encumbrance by counting up pounds is like insisting on modern D&D games having rules for whether your injuries result in fatal Staph-A infections or whether you succumb to PTSD as a result of prolonged subterranean violence. It's like insisting that WW2 wargames include detailed supply rules tracing from raw materials to industrial output to stockpiles to delivery to the front.
To my mind, that sort of thing is (a) out of scope for the kind of heroic fantasy adventure that the game has mostly been about since the 1980s, and (b) uninteresting to the player base writ large.
As I understand it, many newer OSR games are abandoning counting up weight by pounds, not because they don't see survival gameplay as being important (indeed, I should think the opposite is the case), but because gameplay that players find interesting and compelling is more important than any ostensible or alleged "integrity" or "fidelity" to "realism"/"verisimilitude" or what-have-you.
Put another way, having to make decisions about how much loot you can carry out of the dungeon (and therefore having to decide what to leave behind) can be an interesting and compelling part of gameplay (although probably not a central part of any but the most classically-oriented of games), but unless you're a very small niche of the player base, being obliged to count up weight by pounds (or coins) will make such decisions tedious and tiresome instead.
[*] "Onetwothree"
I really don't get what people think is going to happen here. If you want more detailed ship combat rules, they're right there. There's several, professional quality systems available They are 100% right there.
