OK, well, frankly, DDN as it is now and is likely to be in whatever it is, a year, when it is finalized, doesn't even strike me as a good starting point to make a game similar to 4e. It certainly isn't as good a starting point for that as 4e is now, so I don't really understand what the point of DDN IS from my perspective. And yes, it seems like rather a muddle to me. There are some decent ideas, but where is this going?
I've mentioned this before, but it seems to me that DDN is being designed to complement all other editions, not replace them.
Heretofore, the basic WotC model has been "New edition totally replaces old edition", without even easy conversion. I'm not exactly sure why they chose that model, except that perhaps they thought people would happily buy an entire new library of core rules, splats, and adventures, and that would make them the most money. But 5e is not about that. They have the reprints now of every major edition save Classic D&D, and something's probably coming out there. They've re-released their entire library of PDFs, and are going to be reprinting certain historical products. WotC is essentially allowing, nay, encouraging every other edition to compete with the new one.
If 5e were a total stand-alone edition, a la 3e or 4e, this would be pretty stupid from a business standpoint. But 5e is not being designed like that. Nor is it being designed to re-create older editions (which I gather some people were expecting). Instead, it's being designed to flexibly emulate different editions, and permutations thereof. And what this does is allow them to maximize the potential of their entire product history.
So let's say you're a fan of B/X. WotC can come out with pdfs for you, but if their only new product is 4e adventures, you're SOL unless you really like extensive conversions. But now they come out with Next. Next can be configured to run a very rules-light, B/X-like game. They can create adventures for that, with a much lighter conversion load to B/X, and then sell that to players of both Next and B/X.
It's harder to see with, say, 4e because the game is far from finished. But conceivably they could put out an adventure that designed around a granular tactical combat module, characters with more healing options and HP. And such an adventure might appeal to those who've made the jump to Next, but also quite easily be converted to 4e. So even if a 4e fan has no desire to switch over to Next, his preferred edition is still getting support.
And in the meantime, by flipping some switches and adjusting some dials, a Next group that prefers a 4e-ish type game can take that B/X style adventure and use it for their group. The B/X-style Next players can take the 4e-style adventure and use it in their group. Essentially Next gives them an adjustable benchmark for which they can create products used by a variety of players of different editions. PDFs and print-on-demand lets them provide older product without costly overhead. Webtools allow them to provide easy-access conversion rules. They can build on the Monster Builder to create a creature converter that lets you take a Basic monster and turn them into a monster that better fits Standard or Advanced rules, or vice versa. Next and their online tools suite allows them to support all editions in a way that was never before possible.
As I said, what is its purpose? If we have all the other editions out there to play then DDN, as a sort of ersatz version of any of them, has rather little purpose WRT anyone who's already playing one of those other editions (and even new players they bring in can get at least PDFs of most anything now).
As for "we'll make all our adventures for it", yeah, sure. However, with such a balkanized player community what exactly adventures are going to be worth developing and selling? WotC already doesn't seem to have been able to make money on adventures, this isn't going to help that. I also think that 'flipping a few switches' is not enough to turn one type of adventure into another.
I'm just not seeing where the advantage is over simply supporting existing editions of D&D. If DDN ISN'T bringing anything unique or new to the table, then why does it need to have a place at anyone's table?
You're right, it isn't. But it's not intended to be.
True. But again, it's not intended to be. One could also say that D&D Next isn't as a good a starting point for any edition of D&D in comparison to the actual editions themselves. It isn't possible for D&D Next to actually be any and all editions of D&D, let alone do them better than the original versions of those editions.
No argument from me on that. OTOH if you give someone DDN that is supposed to 'play however you want' then aren't you pretty much saying to them "hey, you're going to have to reflect on what you like and how you play before this is likely to work for you". Isn't it better if they give me 4e and you 1e, and some other people 3.5e? Clearly its easy enough for them to reprint all these things, so what gives? I'm lost on the need for another edition of D&D, unless they want to try something completely new.
The question is whether it is worth the effort and whether it is worth creating yet another split in the player base.
Yes. Yes, it is.
Because quite frankly... most people don't care what anyone else is playing. If you keep playing 4E when I switch to 5E... it's no skin off my nose.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.