My experience with hacking and playing games says to me that the strength of 4e is the direct result of the regularity of the mechanics, not something you can add to a different type of implementation by any amount of analysis. Sure, you can try to analyze all the options that are built using highly divergent mechanical underpinnings, but you'll never achieve even 1/100th of the ingenuity that will be applied to prying it apart in the first week by charops. I mean charops broke 4e all the time, but the point was that the very nature of the design was a firewall. You could break a power, or you could combine and pile on certain types of options to an excess and you could produce a character that did exorbitant amounts of damage or whatever, but it wasn't a deep breakage. It wasn't like the 3e Cleric where unless you actively avoided all the decent options like the plague you just outstripped fighters hands down every time, and the number of permutations of things that would produce wonky results was a number theoretically dauntingly large sum. You could plug holes in 3e all day and not even make measurable progress because of the design, not because of some lack of care at making the elements which used that design.
I don't disagree with any of the details of your statement, but I'm not sure I agree with the ultimate conclusion. Many of the 3e balance problems were, as you say, build deeply into the system, but many are fundamental design elements -- not just products of the multitude of options. To pick some examples: Cleric and Druid had a bunch of stacking bonus spells that allowed them to outfight Fighters straight out of the PHB. Wizards advanced in number of spells, the level of spells and the effectiveness of spells while scrolls and wands allowed them to bypass most of the limitations of a finite number of spells per day. Save and BAB numbers didn't work well with how multiclassing allowed you to stack level 1 bonuses. Polymorph magic lets PCs use the monster manual as a self-augmentation menu. These are fundamental problems to the system whether or not you add on a couple dozen splat books.
I agree that there's no way to solve these 3.x problems by hunting down unbalanced combos (except maybe by changing polymorph), but I don't see you couldn't create a new 3.x style game that solved them from the beginning. Will there be unbalanced combos after that? Sure, I'm sure there will be. Searching for unbalanced combos is part of what some people enjoy about the game. But I don't need a game that is safe from charop. I just want a game where I can let my less-sophisticated players choose their own powers without generating useless characters. (And frankly, it's not like 4e was all that good about that. You can get some pretty ineffective characters picking powers from PH1.)
I also think the lessons WotC designers learned from managing powers can be imported into D&DN. Spells can be balanced across classes and levels in the same way that powers were. Yes, it's harder to try that with class abilities, but we've seen maneuvers as an effort in that direction. I don't think I can judge the whether WotC can balance non-spells until we're a little further along in the playtest.
Well, there are a LOT of us, for instance see the "Will there be a game called DDN?" thread or the "Pemertonian Scene Framing" thread(s) where we have put forward a very coherent explanation of how and why DDN is drastically different from 4e in fundamental ways. The things that you mention are no doubt what Mike means, but they are superficial and trivial and a game designer of Mike's caliber must fully understand that DDN will deliver game play that is NOTHING like what 4e delivers for at least a very substantial fraction of 4e fans. In other words what WE consider a '4e style game' is not enabled at all, and the goal appears to be unattainable at this time within the timeframe and within the parameters outlined by Mr Mearls. I guess that's "reasonable people can disagree". I hope it illustrates something of where I'm coming from when I find DDN's design and very goals inadequate from my perspective.
I don't know. I've read those threads and I play 4e now. But I don't view those characteristics as being "superficial or trivial." I think those (along with - at least in theory - skill challenges) are primary characteristics of 4e play.
For my game, 4e provided a fun tactical subgame, encounter-based resources, easier DM prep and a bunch of new fluff (that I picked and chose from, but mostly didn't use). It also solved a number of 3.x problems that were driving me nuts, but it also slowed down combat as my less sophisticated players began taking longer and longer to re-read their character sheets before every combat round.
-KS