I see a lot of D&D Next posts that say vague things, like "4e is missing ... something."
Imagine if someone went to your place of work and said, "Can you fix my problem. It's missing ... something."
Please be more specific in your posts. The more you can give the designers something to hang their hat on, the sooner they can narrow in on the actual issues and address them.
With 5E coming, I've been looking back at older editions trying to nail down an answer to the question "what is D&D to me?"
I revisited D&D by way of the Rules Cyclopedia and AD&D via the 2E PH and 1E DMG, and looked through my 3X stuff and then Pathfinder, and finally came back to take a look at fourth edition.
What I found was pretty interesting, because it resonated strongly with what the developers of 5E are saying about every DM making his own ruleset. I found that no single edition of D&D was "My D&D" - because I never played any of them by the book. Rules were cleaned up or added into older editions or removed from later editions. Some things I thought were canonical parts of the older rules turned out to only be long-standing table tradition and apocrypha. Right up to 3X, we never played the game as written - there, simplifying and streamlining rather than adding in missing mechanics as was more common in the 1E and 2E era.
But, despite all this fiddling, the games all still felt like D&D - the elements in common (random and artificial and arbitrary and broken and ill-considered though they might have been) provided some consistency of experience. Elves don't sleep and are good with bows and longswords. Magic works by the fire-and-forget model, and spells are odd little packages of special case mechanics. Only clerics can heal with magic. At low levels, the system is random and cruel, at high levels, you feel like a striding god upon the earth. The default thin skin of a setting assumes a pseudo-medieval society with Tolkien's non-humans, in which freelance adventurers do dangerous things for loot - basically, if R.E. Howard co-wrote the Lord of the Rings. And lateral thinking - figuring out how to cheat and connive and cheese the monsters rather than directly confronting them - was strongly rewarded. "A fair fight is for suckers" is how we used to describe it.
So for me, D&D came with lots of assumptions, both in the assumed setting elements and in how it handles in play. As 3X advanced, more and more of these assumptions and artifacts were removed - the game became more mechanistic and less random. The concept of the optimized ultimate build grew to prominence, because there were so many more fiddly packages of rules that everyone had access to with which to assemble amazingly effective or amazingly broken (often, the same thing) characters. Hundreds of classes, base and prestige, popped up to provide combinations of fluff and new character abilities. Things started to get really hairy, and the base classes started to look dry and boring compared to the exotic ones. More of the artifacts I found signaled "you are playing D&D" to me were removed or obscured.
And I started to lose interest.
At any given time, I've got a dozen systems cued up to play - D&D is not, and never has been, the only game I want to play. I play D&D when I want D&D, and it turns out that includes a random colelction of stuff and nonsense that I've come to expect. Without that, I start to wonder why I'm not playing a different game entirely, because there are scads of really great fantasy games. For exotic fantasy, I reach for Talislanta. For something with a little grit and psuedo-realism, I'd probably snag Runequest (system, probably not setting). Heroic fantasy, oh... any number of games.
3X was being genetically engineered away from the organically evolved collection of game DNA I'd come to think of as D&D.
So a couple of years pass, I play other things for the most part, and then I hear about 4E. "Hello, it's D&D again. I shall start paying attention."
And I do like some of the initial things I'm hearing, but...
Last night, I cracked open a borrowed 4E PH, and I actually quite liked much of what I read. It's actually a marvelously well-designed game. Or possibly, a well engineered one. All the bits work. There are lots of cool options at first level. Lots of hit points. Ways to heal without clerics. Different elves. Dragon men. A more stylized and extravagant and dynamic art style. And everything explicitly laid out - all the mechanics and all the ways the mechanics can interact. Both instruction manual and strategy guide in one.
But, most of the things I thought of as D&D were missing or altered. The old familiar (sloppy nonsensical) cosmology was different. 1st level characters were tough and competent. There wasn't much room for off-label uses for special abilities which would require DM arbitration. It was all incredibly functional and balanced and neatly organized. It's full of interesting mechanics. But it didn't feel like D&D anymore.
There were other places it jarred into my preferences - too much combat and too many combat rules, the required grid map stuff just made this more obvious/worse. I was looking at the Warlock last night, and thinking, "Hey, these guys seem pretty cool" but then I noticed that they basically consist of a pile of ways to mess somebody up, and a couple of other tricks. Outside of their function in combat, I had not sense of how a Warlock fits into the world, or what they can do with magic beyond messing people up. And that stuff is what always captures my imagination and makes me think about my character a little deeper. Too much strategy, too little cheating. And because it was so tightly designed, it was really hard to mod - so many parts depended on so many other parts, if you change one thing the cascade of consequences was annoyingly hard to correct for. I like games to have carefully preserved areas of ambiguity and interpretation.
But here's the thing - I'd say objectively, 4E is probably the best designed of all previous editions. All the moving parts whir and mesh. It's a great game for certain, even if it isn't entirely to my tastes in some areas. My not liking it does not require that I think it is bad.
If 4E was the first D&D I ever played, I probably would have no objection to it at all (beyond the weight of combat and the grid and whatnot) - to me then, D&D would be the tactics-heavy fantasy roleplaying skirmish game with teleporting elves from the Feywild and honorable dragon guys. The way you might say Exalted is inspired in part by console JRPG's, I'd probably say D&D was inspired in part by WoW.
If you took 4E, ripped out the battlegrid and removed or modified all the mechanics requiring or depending on it (or optionalized it), and gave everybody more non-combat cool stuff and generalized some things, returned a few of the old D&D artifacts, I could probably be quite happy with it, but as it is written I can understand why it lost many longtime players, because of how it lost me.