I think this may be a false premise. It seems to me that it was neither nostalgia nor tradition that made D&D a household name, at its zenith in popularity, and presumably, its most profitable (which is what WotC really wants). Perhaps it was popular due to the game's simpler design? Perhaps it was because a child could pick up the game and learn to play in a day but there was enough meat in it to keep adults happy? Perhaps it was because it only cost $15 to buy all of the rules you needed to get an idea if you wanted to buy the rest of the game? In other words, perhaps it had a broader appeal than just those that "care about good game design" (and who decides what good game design is, anyway?)
If this is the case, and some folks certainly think it is, perhaps broad appeal is exactly what will be achieved with 5e. For now, no one can say and we won't know until we see a boom, bust, or more of the same slow degradation of interest after 5e.
Personally, the model I hope to see is something akin to what Design Mechanism are doing with RuneQuest. That is, they have refined the game in all sorts of ways, that runs quite different to the original game (combat maneuvers, simplified skill system, Legendary abilities, Passions, integrated Characteristic scores as skill bases, magic systems, etc). Yet it is written by a long time RQ veteran who understands the cultural aspects of the game, and produces a game that is recognizable to the original brand.
'Good Game Design' itself is something of a subjective term. We hear time and time again why something is 'good game design', yet it isn't successful because it's not what people actually want.
D&D has got baggage, and it needs to be acknowledged in future game design agendas. Game designers who are responsible to the brand ought to be (and apparently are this time around) aware of this.
I think I'll just reply to both of these at the same time. You both make a few similar points, and it would be easier to say the same thing to both of you.
First, SkyOdin already did a good job of replying to the idea that simplicity and good game are somehow at odds. In fact, they are not. A game can be simplicity itself, with rules that could fit on half of an index card and still be well-designed. In fact, it is generally better to have fewer rules in a better-designed game.
Also, I have little interest in talking about the relative popularity of D&D across different ages. People here on ENWorld claim it was most popular during a some early fad period, WotC claims that 3E and 4E both sold better than that and the hobby has just expanded since those years, and I don't really care which is the truth. Besides, if OD&D was a big fad a few decades ago, I wouldn't expect a return to those rules to bring back that fad any more than I'd expect disco and Pong to make a sudden return. Kids these days are different people than kids from the 70s were. They have different interests and hobbies and tastes.
Also, the people who decide what good game design is are typically fans. Usually fans who have a higher skill level, are more experimental, and have more experience with a wide variety of games within the genre tend to be a better judge than others, but generally the more people you have enjoying the game, the better. Good game design is usually proven by a widely happy and loyal fanbase, good long-term sales, and so on. In a healthier industry than the tabletop RPG market, good game design is often well-rewarded, though just like in movies and such good marketing can surpass the value of good design alone, though good design is usually the best way to maintain fan loyalty.
Whether any given person enjoys a game or not is subjective, but the quality of the game design can be determined objectively. For example, if you poll a reasonable sample group of people who have played the game, you can get an objective measure of how the game made them happy. Taking such information from playtests and applying it to improve the ratio of happy to unhappy players is pretty much the central process of good game design. The quality of a game designer can be determined rather easily based on how well they carry out the basic processes of game design (though a large part of it is built upon experience and intuition). In truth, game design isn't about making the most popular or most commercially successful game, but about making the largest group of people in your target audience happy.
The fact that so many people hated 3E, for example, indicates that it is a rather poorly designed game. It tried to appeal to many people, but D&D fans have been complaining about its horrible balance and bloated rules since it was first released, and you can pretty much blame the entirety of the current fanbase divide on the split between happy and unhappy 3E fans. 4e was mostly targeted at the unhappy 3E fans (the marketing made this as plain as day), and was very successful among that group, so I'd say it was well designed in that regard. Meanwhile, Pathfinder was aimed exclusively at the happy 3E fans, and was rather successful at that, as well, though Paizo used more marketing than game design to secure that business.
I think I'm meandering here, but I guess the basic point of all of this is that game design is a real, valuable thing, even if it is not everything.
Also, I'll say that preserving a game's "baggage" is a potential design goal, but not one that appeals to everyone. I, for one, have no interest at all in D&D's baggage. If I were to create a custom D&D variant exclusive to my preferences, then orcs, elves, dwarves, gith, beholders, rust monsters, and pretty much every other D&D sacred cow would all be on the chopping block. I think their loss would make the game more fun for me. Chasing that baggage is simple chasing fan nostalgia, which is a design goal that can often run counter to the goal of making the game appealing to a much broader audience and making the game fun and accessible. It leads to things like 5E introducing a weak Fighter and overly strong Wizard, even though that that exact choice has been hated and despised by countless D&D fans for years.
):![:]](http://www.enworld.org/forum/images/smilies/devious.png "Devious :]")
