Why the recent focus is pretty simple. The two very visible mass shootings we've had, coupled with the latest one being targeted at rather young children, has awakened an urge to do something politically about the ridiculous level of violence in this country, something that had been just tolerable enough when it was just a constant stream of minor incidents and not moving up to mass shootings.
With the political wind changing, the NRA wants to take the focus off the proliferation of firearms, so they need a scapegoat, and video games are it. Things like Biden's comments aren't because Biden's been secretly biding his time waiting to strike at video games, but because the NRA is a big enough organization with enough clout that you can't just ignore whatever topic they want to demonize. It requires a response of some kind, and for anyone (including the ESA) to just outright dismiss the accusations is to make yourself look as extremist and out-of-touch as, well, the NRA.