Hmm, it would be nice to see a chart about why people sell their games. From my experience as a site operator, it's mainly "game is finished, I want money for the next game".
That is a huge market that cannot be accessed as a developer. This Socom voucher is a way to counter that, in order to bring in added money from the exact game you've been selling.
If anything, this (and that's what I think Sony is targetting most) should hit retailers who re-sell games the most. If they can relay this tactic to their biggest games as well, then retailers will be quick to make a deal with developers where they cut them in on the second hand sales-pie. Retailers are now reluctant to do that as it is pure profit for them.
Over here, there has been a debate about how they could possibly make renting possible again (by doing some sort of DVD-like expensive rental copies for the stores). Retailers apparently backed out of it, as it would mean they had to cut their profits in that sector. Devs and publishers responded by making it illegal.
THAT is the point where a consensus has to be reached between retail and devs. If that can be reached, this will probably all go away.