According to the studio, having its own client will allow the Quake Live team to dedicate more time to updating in-game features "without the worry of how ever-evolving web browsers will affect gameplay and performance."
Quake Live will remain free to play, while offering extended access and features to Premium and Pro members. And to celebrate the New Year, Pro subscribers may now host matches for standard users on all seven Premium game modes. The transition from browser to client should be rather painless with all player profiles, stats, and clan rosters having already been integrated into the standalone client. Only the official forum and external links will resort back to the default web browser.
Those with remaining questions can head over to the Bethesda blog for a full FAQ regarding the Quake Live standalone.