My thoughts on this from a "Sony Marketing" point of view ...
(and yes i played DC already so i know its more arcade then sim ... but were talking marketeer point of view here)
We all know the PS4 launch line-up had some troubles .... DriveClub got delayed (and Watchdogs also) ...
What could SCE do to keep the (racing) masses happy from their point of view ... they hád to launch GT6 close to PS4 market introduction to keep the Racing Sim Fans busy and distract them from the absence of DC ... Yes it still is on PS3... but hey it'll keep them busy ... And the early-adopters can get NFS-Rivals ... So let's rush GT6 ... because initially it had a 2-2014 introduction planned for GT6 ...
(this was decided about 07 /2013) so Kaz was asked to launch an early version of GT6 ... (we all feel the consequences of this)
Of course GT7 has been in development on PS4 as long as Knack, Watchdogs or Driveclub ... they surely have split teams for this with decreasing staff for GT6 ... so updates on GT6 take time ... with gradually less staff to support GT6 ... they are already pulling the plug on GT5 this spring which is quite early .. so more staff can be used to the latest developments (GT6/7) ....
As we all complain about minor issues about GT ... I've tried to approach it from a developers/higher force perspective ... I think it nicely distracts some fans of being negative about the launch line-up ... we don't mind the poor line-up ... GT6 is coming next week for PS3 ...
I was at the pre-launch presentation in october 2013 for PS4 and was surprised then about the number of PS3 games shown and demoed there : GT6, Beyond:two souls, The last of Us, Rain ...
now about three months further in time I get what they were doing ... spreading the attention of all different types of core gamers ... FPS ... Racing .. Sports ... Adventure ... Casual ... they all get their share ... although it was on different platforms ... (PS3/PS4) it was enough spread....
So i think the pressure on Kaz was high to come with an early release of GT6 ... they wanted Sony to win this holiday season battle of 2013
... and i guess they did ...
now we are just the fans of 1 franchise ... and we only represent a minor part in this big landscape ... so we got served pretty well i guess ...
Also I think nowadays Kaz can launch any date ... but Sony calls the shots ... we all heard him say it during the launch of GT5.... "it's out of my hands" ... and I expect he is telling the truth .... Kaz can develop what and when he likes ... but Sony decides when to launch ....