Alphastream
Hero
It was disappointing to me that the survey closed before my group had chance to participate; to me the whole process is far, far too rapid - as opposed to those who feel that it's far too slow.
The survey was a good one, as was the one before it for the friends&family playtest. It dug deep into various aspects of gameplay and had fields in each section for additional comments.
Along those lines, there is a current survey out which everyone should check out. It includes questions about editions you play, where you play, organized play involvement, electronic devices, and more. It isn't focused on D&D Next, but it is a chance to be heard and represented with the kind of game and play you prefer.
The playtest survey likely ended because the team needed to collect data and iterate. They had internal playtests, then produced a limited version. They made a few tweaks, then did friends & family version. They gathered data from f&f and DDXP, then produced the open playtest version. (There were some significant changes at this stage, as well as earlier). They had the survey... and we can read in the various columns how they are moving beyond that.
Yes, they could keep the survey open while they are moving forward, but it requires looking back to pull that in and adjust. From what they communicated they received a ton of survey submissions. They likely can see the trends well enough and need to put their team's energy on working with those results. Once that version is out we will see the next open playtest.
I've also seen it said online that there are continued limited friends & family playtests of things they want to try out.
It seems to me like a pretty good process. Yeah, it would be cool if they gave everyone something new every week, but that has its own issues, such as forcing them to keep external documents constantly up-to-date and explaining the delta. It sounds far easier than it actually is.
We still have great ways to provide feedback: the D&D Next forums. Those forums are read by the team and it is a great place to add in playtest reports or highlight troublesome issues. The best way to contribute is to start a new thread for the specific topic you are sharing and provide the information in a constructive and clear form.