Remember when films would take ages to come out on vhs. Movies back then just felt more special
It's a balance:
Release DVD too early and you canibalise the movie theatre takings
Release DVD too late and people get unauthorised copies
Release DVD at the wrong time and miss out on people buying them as presents (ie for christmas)
One thing's for certain -- release it in one country before another and the internet is flooded with unauthorised copies.
People are still willing to pay 25+$ for an "exclusive" event (concert or sports) but streaming has us accustomed to many movies for little cost. I think the day of simultaneous release of major films on a PPV basis at home (say for 2/3 a movie ticket price) will be here soon. IMAX 3D is 20$ around here already and a regular film ticket is 14$.
I've seen every trek film since Generations at the cinema (didn't see TUC as I was only 9). Nearly didn't get to this one which concerned me, as I was moving house, and getting a grandparent to babysit the kids was tricky. In that time though we watched 3 films on amazon or netflix. If it had been something like Civil War or Star Wars that had clashed, we likely wouldn't have bothered.
However while we were happy paying best part of £40 + the hassle of babysitting and an hour-long round trip drive to watch at the cinema, I'm not sure PPV for £20 would have appealed. Cinema's are an event -- you go out, you get to be switched off from the outside world, you get popcorn and trailers, and there's no pause button (usually takes us over 3 hours to watch a 90 minute film thanks to conversations). It's just not the same at home - but our spending on a film comes out of the same pot we'd spend on an evening meal out, so that's what the cinema is competing with, not with watching a DVD.
PPV means that the internet releases will be a far better quality too (HDMI output into a device that ignores HDCP), meaning time to internet reduces, so PPV has to be aimed at a cheap enough cost that people won't bother -- probably <$10.