In L&L he stated that the next phase of playtesting can be boring and that then planned playtest is to be as large, if not larger, than the one for 3rd Edition. The "boring" comment seems to me an opportunity to contact him and request becoming a part of the next phase. Can't hurt to ask, the worst he can say is no.
It really struck me as a justification. As if they didn't want to (or were not allowed) to have the late rules available for free and now they're trying to sell that to the community.
"Oh, we're ending the playtest. Good job everyone. We can handle it from here because the rest is.... umm... Boring. Yeah, that's it. It's really boring and you wouldn't like it. And we need more information on our playtesters."
Well, the Character Op forums on the Wiz Community are filled with people who LOVE spending their free time comparing powers and balance.
And it often doesn't matter if feedback on a power being broken is coming from a story heavy group or an optimizer group. If a power is not working as intended or there's an obvious abuse then the source is irrelevant.
It wouldn't even be hard to manage the feedback. Just set-up a form.
Have a spot on the playtest website where you pick the file, the page number, and the name of the mechanic in question and then write a sentance or two on why it does not work. And likely the type of problem, be it wording, grammar, math, or an abusive combo.
If a lot of people are writing about the same mechanics then it's worth seeing what they have to say. If only a couple people are writing about a mechanic it's worth less of a look.
It's such a huge missed opportunity. And it really means they
cannot make mistakes. Because they're ending the playtest after doing none of the fine-tuning & balancing (aka the actual playtesting) they had better deliver a product just as good as if 150,000 people gave it a playtesting pass.
They can't afford to have a situation like 3.5e or Essentials again where they release a corrected version of the edition, nor can they have the Day One updates that plagued 4th Edition.
If 5e comes out and they need to immediately patch and fix obvious mistakes... that will really be a big mark against the edition.