In short, I suppose I am saying that I found two problems with 4E. 1) It was grindy; 2) I very rarely took the opposition seriously. The new math helped with
[URL=http://www.enworld.org/forum/usertag.php?do=list&action=hash&hash=1]#1 [/URL] , but -in some cases-made
[URL=http://www.enworld.org/forum/usertag.php?do=list&action=hash&hash=2]#2 [/URL] even worse than it already was. Looking to the DMG 2's Skill Challenge numbers, the new math in that area of the game made
[URL=http://www.enworld.org/forum/usertag.php?do=list&action=hash&hash=2]#2 [/URL] far worse while also increasing the grind I felt during many skill challenges.
I disagree that developing the mechanics and fluff hand-in-hand are only good for one story. You have mechanics designed for one story. However, when designing a "modular" game, I believe it is better to start with mechanics that make sense for the core game and then provide ways to build upon that later. I believe that works better than trying to create a modular game where the mechanics don't really correspond to the core story you are trying to tell, and then you try to patch that later with a variety of different methods which may or may not work and may or may not work to different degrees. I've been lead to believe that because I'm familiar with this:
GURPS Dungeon Fantasy
and find that it works exceptionally well. I know plenty have a dislike of the system, but I found that -for me- it is an excellent example of how to have a D&D style game and tropes while retaining modularity.
I do not expect anywhere near that amount of modularity with D&D 5th Edition. I understand that to "feel like D&D" there need to be certain things set in stone. However, I still feel as though there are placed outside of the d20 family that WoTC should look (and maybe they do) to see how to make their game more 'modular' -at least in the manner that I understand the word to mean a certain thing.
You had mentioned fitting mechanics to a story. Maybe you're right, but that should be what modularity means, right? An earlier complaint I had was that I felt I too often had to bend my vision to the will of 4E instead of vice versa (which I would have preferred.) When playing a particular system, I understand that certain quirks and ideals which are built into a system are something which are going to play a part in the feel of my game. However, I believe that the system -especially a modular one- should give me the ability to fit the mechanics and my vision together and make sense of them while hindering somebody else's ability to do the same as little as possible.
When it comes to 4E, I did not very often feel it was built in a way -mechanically- to allow for the styles of stories other people wanted to tell while not getting in the way of the ones I wanted to tell. That is to say I feel it probably works great for some of the things Pem wants it to do (according to his posts) and others, but it didn't help me create my own vision. More importantly, I felt 4E's mechanics didn't tell 4E's story very well either.
That last sentence brings what I'm trying to say somewhat back together and saves it from my rambling. Mechanics and fluff should -in my opinion- be built with each other in mind. I fully believe that a certain style of mechanics are capable of telling a certain story -even independently from any fluff at all. Likewise, I believe certain styles of fluff tend to suit certain mechanical structures better than others. This is similar to why (imo) we also see differences between how a story plays out in a movie versus in a book. Medium matters, and I believe different mechanics in rpgs can be seen as somewhat analogous to different mediums for telling a story. Using a medium which is ill suited for a style of story or trying to shoehorn a script into a medium which it is ill suited for are both -in my view- equally bad. I feel that, for the most effective entertainment experience, it is best to design your game with both aspects in mind and develop them together.
edit: To summarize, I felt 4E's design was like trying to have Michael Bay direct a shadow puppet presentation of Bambi; using a green screen to CGI in the shadow puppets. There were a lot of sound parts which were excellent in isolation, but they did not complement each other well once fitted together. If you hand me a story telling game and then I find that it doesn't do a very good job of telling my story, I might be inclined to feel I simply chose the wrong product. If you hand me a story telling game and then I find that it doesn't do a very good job of telling the story you advertise that should go with it, I see that as being a problem with the product.