No more or less than what you seem to find scary about the notion of DDN with them, lol. While I am perfectly willing to entertain people's ideas in that regard I don't feel a desire or obligation to invent those mechanics myself. I also don't say that they with absolute certainty exist or will be found, just that all parties should keep an open mind on the subject. If you want to suggest some, that's great. I actually HAVE made MANY concrete suggestions about how I would approach building classes. If you would provide input beyond "no that mechanic can never work for me, can't do that" then we could get somewhereI'm totally happy to do the same.
I don't entirely disagree, we could also limit our discussion to simple core mechanics like AC, defenses, saves, and the most basic low level aspects of class design. That's fine, there's plenty to talk about there in a game design. OTOH WRT to DDN that stuff is largely settled. Some may be revisited slightly, but there's nothing radically controversial there, outside of some few things that might inhibit a more 4e-like design on top of that. Of course Mike HAS stated that he's not going for various different either/or options like different magic systems (there's been some back and forth on this sort of thing, but the most definitive statements have been more on the no side IMHO). So, we'd be more probably speculating when it came to say "modules that work like 4e" etc on 3PP content I would think.
I think part of the issue is that discussion of individual mechanics are being discussed in the larger context of editions and not on their own. When someone says they don't like a specific mechanic, it is often interpreted as not liking an edition or disliking all aspects of an edition just because that mechanic exists within the edition. I don't like 3e because TOB introduced encounter-based resources. I don't dislike 4e rituals because I don't like encounter-based resources. I don't dislike 1e because I like stances. But since we're talking about all of these things in the context of 5e everything gets jumbled together.
I would love to see a layered approach to 5e. I would love to see each edition be accurately embraced by 5e in a way that doesn't prevent anyone from playing their game. I still firmly believe that there are more similarities between editions than differences and I love being able to pick and choose parts of each edition that I like, without feeling a need to only play one particular edition. I enjoy different flavors of D&D.