I have a different take on this. These poll companies are supplying their customers with exactly what their customers want. Their customers (the media) obviously are not concerned about accuracy (remember the Dan Rather "fake but accurate" mantra). They are concerned with putting a pro Democrat slant to all news.
So with this logic, these companies are giving them exactly what they want.
I considered that theory as well, but if that were the case they’d all be commissioning “registered voter” polls. It also doesn’t explain the polls that Fox News is showing, which also show Obama in the lead.