1. Lack of online excitement/hype 6 months out from release.
We've had a playtest going for over a year, and it was clear from the start that the release date pretty much had to be 2014 if it wasn't 2013. As far as I know, the marketing push hasn't started yet. So why would there be online excitement?
2. A fragmented player base.
True, this is an issue for 5E. Then again, 5E has some advantages that shouldn't be discounted. In particular, it has an opportunity to exploit Pathfinder's greatest weakness--the need to maintain backward compatibility with 3E.
One of PF's big selling points is that you can keep using your 3E material, and Paizo can't abandon that without losing a huge chunk of players. But that severely limits their ability to innovate on the mechanics, which means that Pathfinder players who
aren't heavily invested in 3E might be interested in a game that fixes some of 3E's system issues while retaining the conceptual core of D&D.
Obviously, 5E would be in a better spot today if the 4E/PF split had never happened. But if that were the case, 5E probably wouldn't be happening yet.
As for the OSR, I don't see that as an issue for 5E. Sure, some people have abandoned Wizards-era D&D for a return to TSR-style gaming. But the flip side of that is that there are many groups that never got on board with 3E in the first place, and with 5E making a deliberate effort to be "old-school friendly," some of them might be open to making the jump at last. I'd say it's a wash.
5. Lack of big name designers. A popular designers name will sell copies of an RPG. Gygax back in the day, Monte Cook and Numenera these days. D&DN lacks a big name like Gygax, Mentzer, Cook (either one) who have designed a popular edition of D&D.
Oh, come on. Are you seriously claiming that it was Gary Gygax's name that sold AD&D, or Monte Cook's name that sold 3E? Certainly Cook had some successes ("Dark Space") before joining TSR, but no more than Mearls had before joining Wizards ("Iron Heroes"). Cook became a big name
after 3E was published, just like Gygax after AD&D. D&D sold
them.
6. D&DN lacks a clear focus and target audience.
It's not at all evident that a "clear focus" is a good thing for D&D. 4E tried having a clear focus and bombed. D&D is most successful when it's versatile and open to customization. On that front, 5E looks like being the best edition since AD&D.
8. Forum numbers on wizards.com forums are way down it seems. The 4E forums are very quiet, the FR forums are almost a ghost town.
That's what happens when you stop releasing product. Your company forums go quiet.
10. Lack of focus in the play test packets. Put bluntly the play test was all over the place.
Play. Test. As in, you give a system to people to play, as a way to test the system. It's about collecting information, and you don't collect any information by doing the same test twice. This complaint is just ridiculous.